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Hypothesis Examples

A hypothesis is a prediction of the outcome of a test. It forms the basis for designing an experiment in the scientific method . A good hypothesis is testable, meaning it makes a prediction you can check with observation or experimentation. Here are different hypothesis examples.

Null Hypothesis Examples

The null hypothesis (H 0 ) is also known as the zero-difference or no-difference hypothesis. It predicts that changing one variable ( independent variable ) will have no effect on the variable being measured ( dependent variable ). Here are null hypothesis examples:

• Plant growth is unaffected by temperature.
• If you increase temperature, then solubility of salt will increase.
• Incidence of skin cancer is unrelated to ultraviolet light exposure.
• All brands of light bulb last equally long.
• Cats have no preference for the color of cat food.
• All daisies have the same number of petals.

Sometimes the null hypothesis shows there is a suspected correlation between two variables. For example, if you think plant growth is affected by temperature, you state the null hypothesis: “Plant growth is not affected by temperature.” Why do you do this, rather than say “If you change temperature, plant growth will be affected”? The answer is because it’s easier applying a statistical test that shows, with a high level of confidence, a null hypothesis is correct or incorrect.

Research Hypothesis Examples

A research hypothesis (H 1 ) is a type of hypothesis used to design an experiment. This type of hypothesis is often written as an if-then statement because it’s easy identifying the independent and dependent variables and seeing how one affects the other. If-then statements explore cause and effect. In other cases, the hypothesis shows a correlation between two variables. Here are some research hypothesis examples:

• If you leave the lights on, then it takes longer for people to fall asleep.
• If you refrigerate apples, they last longer before going bad.
• If you keep the curtains closed, then you need less electricity to heat or cool the house (the electric bill is lower).
• If you leave a bucket of water uncovered, then it evaporates more quickly.
• Goldfish lose their color if they are not exposed to light.
• Workers who take vacations are more productive than those who never take time off.

Is It Okay to Disprove a Hypothesis?

Yes! You may even choose to write your hypothesis in such a way that it can be disproved because it’s easier to prove a statement is wrong than to prove it is right. In other cases, if your prediction is incorrect, that doesn’t mean the science is bad. Revising a hypothesis is common. It demonstrates you learned something you did not know before you conducted the experiment.

Test yourself with a Scientific Method Quiz .

• Mellenbergh, G.J. (2008). Chapter 8: Research designs: Testing of research hypotheses. In H.J. Adèr & G.J. Mellenbergh (eds.), Advising on Research Methods: A Consultant’s Companion . Huizen, The Netherlands: Johannes van Kessel Publishing.
• Popper, Karl R. (1959). The Logic of Scientific Discovery . Hutchinson & Co. ISBN 3-1614-8410-X.
• Schick, Theodore; Vaughn, Lewis (2002). How to think about weird things: critical thinking for a New Age . Boston: McGraw-Hill Higher Education. ISBN 0-7674-2048-9.
• Tobi, Hilde; Kampen, Jarl K. (2018). “Research design: the methodology for interdisciplinary research framework”. Quality & Quantity . 52 (3): 1209–1225. doi: 10.1007/s11135-017-0513-8

Related Posts

15 Hypothesis Examples

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A hypothesis is defined as a testable prediction , and is used primarily in scientific experiments as a potential or predicted outcome that scientists attempt to prove or disprove (Atkinson et al., 2021; Tan, 2022).

In my types of hypothesis article, I outlined 13 different hypotheses, including the directional hypothesis (which makes a prediction about an effect of a treatment will be positive or negative) and the associative hypothesis (which makes a prediction about the association between two variables).

This article will dive into some interesting examples of hypotheses and examine potential ways you might test each one.

Hypothesis Examples

1. “inadequate sleep decreases memory retention”.

Field: Psychology

Type: Causal Hypothesis A causal hypothesis explores the effect of one variable on another. This example posits that a lack of adequate sleep causes decreased memory retention. In other words, if you are not getting enough sleep, your ability to remember and recall information may suffer.

How to Test:

To test this hypothesis, you might devise an experiment whereby your participants are divided into two groups: one receives an average of 8 hours of sleep per night for a week, while the other gets less than the recommended sleep amount.

During this time, all participants would daily study and recall new, specific information. You’d then measure memory retention of this information for both groups using standard memory tests and compare the results.

Should the group with less sleep have statistically significant poorer memory scores, the hypothesis would be supported.

Ensuring the integrity of the experiment requires taking into account factors such as individual health differences, stress levels, and daily nutrition.

Relevant Study: Sleep loss, learning capacity and academic performance (Curcio, Ferrara & De Gennaro, 2006)

2. “Increase in Temperature Leads to Increase in Kinetic Energy”

Field: Physics

Type: Deductive Hypothesis The deductive hypothesis applies the logic of deductive reasoning – it moves from a general premise to a more specific conclusion. This specific hypothesis assumes that as temperature increases, the kinetic energy of particles also increases – that is, when you heat something up, its particles move around more rapidly.

This hypothesis could be examined by heating a gas in a controlled environment and capturing the movement of its particles as a function of temperature.

You’d gradually increase the temperature and measure the kinetic energy of the gas particles with each increment. If the kinetic energy consistently rises with the temperature, your hypothesis gets supporting evidence.

Variables such as pressure and volume of the gas would need to be held constant to ensure validity of results.

3. “Children Raised in Bilingual Homes Develop Better Cognitive Skills”

Field: Psychology/Linguistics

Type: Comparative Hypothesis The comparative hypothesis posits a difference between two or more groups based on certain variables. In this context, you might propose that children raised in bilingual homes have superior cognitive skills compared to those raised in monolingual homes.

Testing this hypothesis could involve identifying two groups of children: those raised in bilingual homes, and those raised in monolingual homes.

Cognitive skills in both groups would be evaluated using a standard cognitive ability test at different stages of development. The examination would be repeated over a significant time period for consistency.

If the group raised in bilingual homes persistently scores higher than the other, the hypothesis would thereby be supported.

The challenge for the researcher would be controlling for other variables that could impact cognitive development, such as socio-economic status, education level of parents, and parenting styles.

Relevant Study: The cognitive benefits of being bilingual (Marian & Shook, 2012)

4. “High-Fiber Diet Leads to Lower Incidences of Cardiovascular Diseases”

Field: Medicine/Nutrition

Type: Alternative Hypothesis The alternative hypothesis suggests an alternative to a null hypothesis. In this context, the implied null hypothesis could be that diet has no effect on cardiovascular health, which the alternative hypothesis contradicts by suggesting that a high-fiber diet leads to fewer instances of cardiovascular diseases.

To test this hypothesis, a longitudinal study could be conducted on two groups of participants; one adheres to a high-fiber diet, while the other follows a diet low in fiber.

After a fixed period, the cardiovascular health of participants in both groups could be analyzed and compared. If the group following a high-fiber diet has a lower number of recorded cases of cardiovascular diseases, it would provide evidence supporting the hypothesis.

Control measures should be implemented to exclude the influence of other lifestyle and genetic factors that contribute to cardiovascular health.

Relevant Study: Dietary fiber, inflammation, and cardiovascular disease (King, 2005)

5. “Gravity Influences the Directional Growth of Plants”

Field: Agronomy / Botany

Type: Explanatory Hypothesis An explanatory hypothesis attempts to explain a phenomenon. In this case, the hypothesis proposes that gravity affects how plants direct their growth – both above-ground (toward sunlight) and below-ground (towards water and other resources).

The testing could be conducted by growing plants in a rotating cylinder to create artificial gravity.

Observations on the direction of growth, over a specified period, can provide insights into the influencing factors. If plants consistently direct their growth in a manner that indicates the influence of gravitational pull, the hypothesis is substantiated.

It is crucial to ensure that other growth-influencing factors, such as light and water, are uniformly distributed so that only gravity influences the directional growth.

6. “The Implementation of Gamified Learning Improves Students’ Motivation”

Field: Education

Type: Relational Hypothesis The relational hypothesis describes the relation between two variables. Here, the hypothesis is that the implementation of gamified learning has a positive effect on the motivation of students.

To validate this proposition, two sets of classes could be compared: one that implements a learning approach with game-based elements, and another that follows a traditional learning approach.

The students’ motivation levels could be gauged by monitoring their engagement, performance, and feedback over a considerable timeframe.

If the students engaged in the gamified learning context present higher levels of motivation and achievement, the hypothesis would be supported.

Control measures ought to be put into place to account for individual differences, including prior knowledge and attitudes towards learning.

Relevant Study: Does educational gamification improve students’ motivation? (Chapman & Rich, 2018)

7. “Mathematics Anxiety Negatively Affects Performance”

Field: Educational Psychology

Type: Research Hypothesis The research hypothesis involves making a prediction that will be tested. In this case, the hypothesis proposes that a student’s anxiety about math can negatively influence their performance in math-related tasks.

To assess this hypothesis, researchers must first measure the mathematics anxiety levels of a sample of students using a validated instrument, such as the Mathematics Anxiety Rating Scale.

Then, the students’ performance in mathematics would be evaluated through standard testing. If there’s a negative correlation between the levels of math anxiety and math performance (meaning as anxiety increases, performance decreases), the hypothesis would be supported.

It would be crucial to control for relevant factors such as overall academic performance and previous mathematical achievement.

8. “Disruption of Natural Sleep Cycle Impairs Worker Productivity”

Field: Organizational Psychology

Type: Operational Hypothesis The operational hypothesis involves defining the variables in measurable terms. In this example, the hypothesis posits that disrupting the natural sleep cycle, for instance through shift work or irregular working hours, can lessen productivity among workers.

To test this hypothesis, you could collect data from workers who maintain regular working hours and those with irregular schedules.

Measuring productivity could involve examining the worker’s ability to complete tasks, the quality of their work, and their efficiency.

If workers with interrupted sleep cycles demonstrate lower productivity compared to those with regular sleep patterns, it would lend support to the hypothesis.

Consideration should be given to potential confounding variables such as job type, worker age, and overall health.

9. “Regular Physical Activity Reduces the Risk of Depression”

Field: Health Psychology

Type: Predictive Hypothesis A predictive hypothesis involves making a prediction about the outcome of a study based on the observed relationship between variables. In this case, it is hypothesized that individuals who engage in regular physical activity are less likely to suffer from depression.

Longitudinal studies would suit to test this hypothesis, tracking participants’ levels of physical activity and their mental health status over time.

The level of physical activity could be self-reported or monitored, while mental health status could be assessed using standard diagnostic tools or surveys.

If data analysis shows that participants maintaining regular physical activity have a lower incidence of depression, this would endorse the hypothesis.

However, care should be taken to control other lifestyle and behavioral factors that could intervene with the results.

Relevant Study: Regular physical exercise and its association with depression (Kim, 2022)

10. “Regular Meditation Enhances Emotional Stability”

Type: Empirical Hypothesis In the empirical hypothesis, predictions are based on amassed empirical evidence . This particular hypothesis theorizes that frequent meditation leads to improved emotional stability, resonating with numerous studies linking meditation to a variety of psychological benefits.

Earlier studies reported some correlations, but to test this hypothesis directly, you’d organize an experiment where one group meditates regularly over a set period while a control group doesn’t.

Both groups’ emotional stability levels would be measured at the start and end of the experiment using a validated emotional stability assessment.

If regular meditators display noticeable improvements in emotional stability compared to the control group, the hypothesis gains credit.

You’d have to ensure a similar emotional baseline for all participants at the start to avoid skewed results.

11. “Children Exposed to Reading at an Early Age Show Superior Academic Progress”

Type: Directional Hypothesis The directional hypothesis predicts the direction of an expected relationship between variables. Here, the hypothesis anticipates that early exposure to reading positively affects a child’s academic advancement.

A longitudinal study tracking children’s reading habits from an early age and their consequent academic performance could validate this hypothesis.

Parents could report their children’s exposure to reading at home, while standardized school exam results would provide a measure of academic achievement.

If the children exposed to early reading consistently perform better acadically, it gives weight to the hypothesis.

However, it would be important to control for variables that might impact academic performance, such as socioeconomic background, parental education level, and school quality.

12. “Adopting Energy-efficient Technologies Reduces Carbon Footprint of Industries”

Field: Environmental Science

Type: Descriptive Hypothesis A descriptive hypothesis predicts the existence of an association or pattern related to variables. In this scenario, the hypothesis suggests that industries adopting energy-efficient technologies will resultantly show a reduced carbon footprint.

Global industries making use of energy-efficient technologies could track their carbon emissions over time. At the same time, others not implementing such technologies continue their regular tracking.

After a defined time, the carbon emission data of both groups could be compared. If industries that adopted energy-efficient technologies demonstrate a notable reduction in their carbon footprints, the hypothesis would hold strong.

In the experiment, you would exclude variations brought by factors such as industry type, size, and location.

13. “Reduced Screen Time Improves Sleep Quality”

Type: Simple Hypothesis The simple hypothesis is a prediction about the relationship between two variables, excluding any other variables from consideration. This example posits that by reducing time spent on devices like smartphones and computers, an individual should experience improved sleep quality.

A sample group would need to reduce their daily screen time for a pre-determined period. Sleep quality before and after the reduction could be measured using self-report sleep diaries and objective measures like actigraphy, monitoring movement and wakefulness during sleep.

If the data shows that sleep quality improved post the screen time reduction, the hypothesis would be validated.

Other aspects affecting sleep quality, like caffeine intake, should be controlled during the experiment.

Relevant Study: Screen time use impacts low‐income preschool children’s sleep quality, tiredness, and ability to fall asleep (Waller et al., 2021)

14. Engaging in Brain-Training Games Improves Cognitive Functioning in Elderly

Field: Gerontology

Type: Inductive Hypothesis Inductive hypotheses are based on observations leading to broader generalizations and theories. In this context, the hypothesis deduces from observed instances that engaging in brain-training games can help improve cognitive functioning in the elderly.

A longitudinal study could be conducted where an experimental group of elderly people partakes in regular brain-training games.

Their cognitive functioning could be assessed at the start of the study and at regular intervals using standard neuropsychological tests.

If the group engaging in brain-training games shows better cognitive functioning scores over time compared to a control group not playing these games, the hypothesis would be supported.

15. Farming Practices Influence Soil Erosion Rates

Type: Null Hypothesis A null hypothesis is a negative statement assuming no relationship or difference between variables. The hypothesis in this context asserts there’s no effect of different farming practices on the rates of soil erosion.

Comparing soil erosion rates in areas with different farming practices over a considerable timeframe could help test this hypothesis.

If, statistically, the farming practices do not lead to differences in soil erosion rates, the null hypothesis is accepted.

However, if marked variation appears, the null hypothesis is rejected, meaning farming practices do influence soil erosion rates. It would be crucial to control for external factors like weather, soil type, and natural vegetation.

The variety of hypotheses mentioned above underscores the diversity of research constructs inherent in different fields, each with its unique purpose and way of testing.

While researchers may develop hypotheses primarily as tools to define and narrow the focus of the study, these hypotheses also serve as valuable guiding forces for the data collection and analysis procedures, making the research process more efficient and direction-focused.

Hypotheses serve as a compass for any form of academic research. The diverse examples provided, from Psychology to Educational Studies, Environmental Science to Gerontology, clearly demonstrate how certain hypotheses suit specific fields more aptly than others.

It is important to underline that although these varied hypotheses differ in their structure and methods of testing, each endorses the fundamental value of empiricism in research. Evidence-based decision making remains at the heart of scholarly inquiry, regardless of the research field, thus aligning all hypotheses to the core purpose of scientific investigation.

Testing hypotheses is an essential part of the scientific method . By doing so, researchers can either confirm their predictions, giving further validity to an existing theory, or they might uncover new insights that could potentially shift the field’s understanding of a particular phenomenon. In either case, hypotheses serve as the stepping stones for scientific exploration and discovery.

Atkinson, P., Delamont, S., Cernat, A., Sakshaug, J. W., & Williams, R. A. (2021).  SAGE research methods foundations . SAGE Publications Ltd.

Curcio, G., Ferrara, M., & De Gennaro, L. (2006). Sleep loss, learning capacity and academic performance.  Sleep medicine reviews ,  10 (5), 323-337.

Kim, J. H. (2022). Regular physical exercise and its association with depression: A population-based study short title: Exercise and depression.  Psychiatry Research ,  309 , 114406.

King, D. E. (2005). Dietary fiber, inflammation, and cardiovascular disease.  Molecular nutrition & food research ,  49 (6), 594-600.

Marian, V., & Shook, A. (2012, September). The cognitive benefits of being bilingual. In Cerebrum: the Dana forum on brain science (Vol. 2012). Dana Foundation.

Tan, W. C. K. (2022). Research Methods: A Practical Guide For Students And Researchers (Second Edition) . World Scientific Publishing Company.

Waller, N. A., Zhang, N., Cocci, A. H., D’Agostino, C., Wesolek‐Greenson, S., Wheelock, K., … & Resnicow, K. (2021). Screen time use impacts low‐income preschool children’s sleep quality, tiredness, and ability to fall asleep. Child: care, health and development, 47 (5), 618-626.

• Chris Drew (PhD) https://helpfulprofessor.com/author/chris-drew-phd-2/ 10 Reasons you’re Perpetually Single
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• How to Write a Strong Hypothesis | Guide & Examples

How to Write a Strong Hypothesis | Guide & Examples

Published on 6 May 2022 by Shona McCombes .

A hypothesis is a statement that can be tested by scientific research. If you want to test a relationship between two or more variables, you need to write hypotheses before you start your experiment or data collection.

Table of contents

What is a hypothesis, developing a hypothesis (with example), hypothesis examples, frequently asked questions about writing hypotheses.

A hypothesis states your predictions about what your research will find. It is a tentative answer to your research question that has not yet been tested. For some research projects, you might have to write several hypotheses that address different aspects of your research question.

A hypothesis is not just a guess – it should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

Variables in hypotheses

Hypotheses propose a relationship between two or more variables . An independent variable is something the researcher changes or controls. A dependent variable is something the researcher observes and measures.

In this example, the independent variable is exposure to the sun – the assumed cause . The dependent variable is the level of happiness – the assumed effect .

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Step 1: ask a question.

Writing a hypothesis begins with a research question that you want to answer. The question should be focused, specific, and researchable within the constraints of your project.

Step 2: Do some preliminary research

Your initial answer to the question should be based on what is already known about the topic. Look for theories and previous studies to help you form educated assumptions about what your research will find.

At this stage, you might construct a conceptual framework to identify which variables you will study and what you think the relationships are between them. Sometimes, you’ll have to operationalise more complex constructs.

Step 3: Formulate your hypothesis

Now you should have some idea of what you expect to find. Write your initial answer to the question in a clear, concise sentence.

Step 4: Refine your hypothesis

You need to make sure your hypothesis is specific and testable. There are various ways of phrasing a hypothesis, but all the terms you use should have clear definitions, and the hypothesis should contain:

• The relevant variables
• The specific group being studied
• The predicted outcome of the experiment or analysis

Step 5: Phrase your hypothesis in three ways

To identify the variables, you can write a simple prediction in if … then form. The first part of the sentence states the independent variable and the second part states the dependent variable.

In academic research, hypotheses are more commonly phrased in terms of correlations or effects, where you directly state the predicted relationship between variables.

If you are comparing two groups, the hypothesis can state what difference you expect to find between them.

Step 6. Write a null hypothesis

If your research involves statistical hypothesis testing , you will also have to write a null hypothesis. The null hypothesis is the default position that there is no association between the variables. The null hypothesis is written as H 0 , while the alternative hypothesis is H 1 or H a .

Hypothesis testing is a formal procedure for investigating our ideas about the world using statistics. It is used by scientists to test specific predictions, called hypotheses , by calculating how likely it is that a pattern or relationship between variables could have arisen by chance.

A hypothesis is not just a guess. It should be based on existing theories and knowledge. It also has to be testable, which means you can support or refute it through scientific research methods (such as experiments, observations, and statistical analysis of data).

A research hypothesis is your proposed answer to your research question. The research hypothesis usually includes an explanation (‘ x affects y because …’).

A statistical hypothesis, on the other hand, is a mathematical statement about a population parameter. Statistical hypotheses always come in pairs: the null and alternative hypotheses. In a well-designed study , the statistical hypotheses correspond logically to the research hypothesis.

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• Pick a topic
• Determine a problem
• Investigate your problem
• Formulate a hypothesis

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• Define the problem
• Select your variables
• Draft your hypothesis
• Write your procedure
• Get permissions
• Test your hypothesis
• Compile your data
• Write your research paper
• Construct your exhibit
• Prepare your presentation
• Show Time! Pre-science fair checklist
• Submit your paperwork

Step 5C: Draft your hypothesis

Your draft hypothesis statement should include the following:

• the question or problem you are trying to answer;
• how the independent variable will be changed;
• the measurable or testable effect it will have on the dependent variable ;
• and your best guess as to what you think the outcome will be.

Use the space on the Experiment Design Worksheet to draft your hypothesis statement.

Tip: A hypothesis problem can be stated in different ways.  Here are some examples:

As a question: Does temperature affect the rate of plant growth? As a statement: Temperature may affect the rate of plant growth. As an if/then statement: If temperature is related to the rate of plant growth, then changing the temperature will change the rate of plant growth.

A hypothesis is a statement that predicts the outcome of your experiment, and is informed by the research you have done on your topic.

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A hypothesis is an explanation for a set of observations. Hypothesis examples can help you understand how this scientific method works.

Although you could state a scientific hypothesis in various ways, most hypotheses are either "If, then" statements or forms of the null hypothesis. The null hypothesis is sometimes called the "no difference" hypothesis. The null hypothesis is good for experimentation because it's simple to disprove. If you disprove a null hypothesis, that is evidence for a relationship between the variables you are examining.

Hypotheses Examples: Null

• All daisies have the same number of petals.
• Hyperactivity is unrelated to eating sugar.
• The number of pets in a household is unrelated to the number of people living in it.
• A person's preference for a shirt is unrelated to its color.

Hypotheses Examples: If, Then

• If you get at least 6 hours of sleep, you will do better on tests than if you get less sleep.
• If you drop a ball, it will fall toward the ground.
• If you drink coffee before going to bed, then it will take longer to fall asleep.
• If you cover a wound with a bandage, then it will heal with less scarring.

Improving a Hypothesis to Make It Testable

You may wish to revise your first hypothesis to make it easier to design an experiment to test. For example, let's say you have a bad breakout the morning after eating a lot of greasy food. You may wonder if there is a correlation between eating greasy food and getting pimples. You propose the hypothesis example:

Eating greasy food causes pimples.

Next, you need to design an experiment to test this hypothesis. Let's say you decide to eat greasy food every day for a week and record the effect on your face. Then, as a control, you'll avoid greasy food for the next week and see what happens. Now, this is not a good experiment because it does not take into account other factors such as hormone levels, stress, sun exposure, exercise, or any number of other variables that might conceivably affect your skin.

The problem is that you cannot assign cause to your effect . If you eat french fries for a week and suffer a breakout, can you definitely say it was the grease in the food that caused it? Maybe it was the salt. Maybe it was the potato. Maybe it was unrelated to diet. You can't prove your hypothesis. It's much easier to disprove a hypothesis.

So, let's restate the hypothesis to make it easier to evaluate the data:

Getting pimples is unaffected by eating greasy food.

So, if you eat fatty food every day for a week and suffer breakouts and then don't break out the week that you avoid greasy food, you can be pretty sure something is up. Can you disprove the hypothesis? Probably not, since it is so hard to assign cause and effect. However, you can make a strong case that there is some relationship between diet and acne.

If your skin stays clear for the entire test, you may decide to accept your hypothesis . Again, you didn't prove or disprove anything, which is fine

• Null Hypothesis Examples
• The Role of a Controlled Variable in an Experiment
• Random Error vs. Systematic Error
• What Is a Testable Hypothesis?
• What Are the Elements of a Good Hypothesis?
• Scientific Hypothesis Examples
• What Is a Hypothesis? (Science)
• Scientific Method Vocabulary Terms
• Scientific Method Flow Chart
• Understanding Simple vs Controlled Experiments
• Six Steps of the Scientific Method
• What Is an Experimental Constant?
• What Is the Difference Between a Control Variable and Control Group?
• Scientific Variable
• What Is a Controlled Experiment?
• DRY MIX Experiment Variables Acronym

What is a hypothesis?

No.  A hypothesis is sometimes described as an educated guess.  That's not the same thing as a guess and not really a good description of a hypothesis either.  Let's try working through an example.

If you put an ice cube on a plate and place it on the table, what will happen?  A very young child might guess that it will still be there in a couple of hours.  Most people would agree with the hypothesis that:

An ice cube will melt in less than 30 minutes.

You could put sit and watch the ice cube melt and think you've proved a hypothesis.  But you will have missed some important steps.

For a good science fair project you need to do quite a bit of research before any experimenting.  Start by finding some information about how and why water melts.  You could read a book, do a bit of Google searching, or even ask an expert.  For our example, you could learn about how temperature and air pressure can change the state of water.  Don't forget that elevation above sea level changes air pressure too.

Now, using all your research, try to restate that hypothesis.

An ice cube will melt in less than 30 minutes in a room at sea level with a temperature of 20C or 68F.

But wait a minute.  What is the ice made from?  What if the ice cube was made from salt water, or you sprinkled salt on a regular ice cube?  Time for some more research.  Would adding salt make a difference?  Turns out it does.  Would other chemicals change the melting time?

Using this new information, let's try that hypothesis again.

An ice cube made with tap water will melt in less than 30 minutes in a room at sea level with a temperature of 20C or 68F.

Does that seem like an educated guess?  No, it sounds like you are stating the obvious.

At this point, it is obvious only because of your research.  You haven't actually done the experiment.  Now it's time to run the experiment to support the hypothesis.

A hypothesis isn't an educated guess.  It is a tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.

Once you do the experiment and find out if it supports the hypothesis, it becomes part of scientific theory.

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What is a scientific hypothesis?

It's the initial building block in the scientific method.

Hypothesis basics

What makes a hypothesis testable.

• Types of hypotheses
• Hypothesis versus theory

Additional resources

Bibliography.

A scientific hypothesis is a tentative, testable explanation for a phenomenon in the natural world. It's the initial building block in the scientific method . Many describe it as an "educated guess" based on prior knowledge and observation. While this is true, a hypothesis is more informed than a guess. While an "educated guess" suggests a random prediction based on a person's expertise, developing a hypothesis requires active observation and background research. 

The basic idea of a hypothesis is that there is no predetermined outcome. For a solution to be termed a scientific hypothesis, it has to be an idea that can be supported or refuted through carefully crafted experimentation or observation. This concept, called falsifiability and testability, was advanced in the mid-20th century by Austrian-British philosopher Karl Popper in his famous book "The Logic of Scientific Discovery" (Routledge, 1959).

A key function of a hypothesis is to derive predictions about the results of future experiments and then perform those experiments to see whether they support the predictions.

A hypothesis is usually written in the form of an if-then statement, which gives a possibility (if) and explains what may happen because of the possibility (then). The statement could also include "may," according to California State University, Bakersfield .

Here are some examples of hypothesis statements:

• If garlic repels fleas, then a dog that is given garlic every day will not get fleas.
• If sugar causes cavities, then people who eat a lot of candy may be more prone to cavities.
• If ultraviolet light can damage the eyes, then maybe this light can cause blindness.

A useful hypothesis should be testable and falsifiable. That means that it should be possible to prove it wrong. A theory that can't be proved wrong is nonscientific, according to Karl Popper's 1963 book " Conjectures and Refutations ."

An example of an untestable statement is, "Dogs are better than cats." That's because the definition of "better" is vague and subjective. However, an untestable statement can be reworded to make it testable. For example, the previous statement could be changed to this: "Owning a dog is associated with higher levels of physical fitness than owning a cat." With this statement, the researcher can take measures of physical fitness from dog and cat owners and compare the two.

Types of scientific hypotheses

In an experiment, researchers generally state their hypotheses in two ways. The null hypothesis predicts that there will be no relationship between the variables tested, or no difference between the experimental groups. The alternative hypothesis predicts the opposite: that there will be a difference between the experimental groups. This is usually the hypothesis scientists are most interested in, according to the University of Miami .

For example, a null hypothesis might state, "There will be no difference in the rate of muscle growth between people who take a protein supplement and people who don't." The alternative hypothesis would state, "There will be a difference in the rate of muscle growth between people who take a protein supplement and people who don't."

If the results of the experiment show a relationship between the variables, then the null hypothesis has been rejected in favor of the alternative hypothesis, according to the book " Research Methods in Psychology " (​​BCcampus, 2015). 

There are other ways to describe an alternative hypothesis. The alternative hypothesis above does not specify a direction of the effect, only that there will be a difference between the two groups. That type of prediction is called a two-tailed hypothesis. If a hypothesis specifies a certain direction — for example, that people who take a protein supplement will gain more muscle than people who don't — it is called a one-tailed hypothesis, according to William M. K. Trochim , a professor of Policy Analysis and Management at Cornell University.

Sometimes, errors take place during an experiment. These errors can happen in one of two ways. A type I error is when the null hypothesis is rejected when it is true. This is also known as a false positive. A type II error occurs when the null hypothesis is not rejected when it is false. This is also known as a false negative, according to the University of California, Berkeley . 

A hypothesis can be rejected or modified, but it can never be proved correct 100% of the time. For example, a scientist can form a hypothesis stating that if a certain type of tomato has a gene for red pigment, that type of tomato will be red. During research, the scientist then finds that each tomato of this type is red. Though the findings confirm the hypothesis, there may be a tomato of that type somewhere in the world that isn't red. Thus, the hypothesis is true, but it may not be true 100% of the time.

Scientific theory vs. scientific hypothesis

The best hypotheses are simple. They deal with a relatively narrow set of phenomena. But theories are broader; they generally combine multiple hypotheses into a general explanation for a wide range of phenomena, according to the University of California, Berkeley . For example, a hypothesis might state, "If animals adapt to suit their environments, then birds that live on islands with lots of seeds to eat will have differently shaped beaks than birds that live on islands with lots of insects to eat." After testing many hypotheses like these, Charles Darwin formulated an overarching theory: the theory of evolution by natural selection.

"Theories are the ways that we make sense of what we observe in the natural world," Tanner said. "Theories are structures of ideas that explain and interpret facts." 

• Read more about writing a hypothesis, from the American Medical Writers Association.
• Find out why a hypothesis isn't always necessary in science, from The American Biology Teacher.
• Learn about null and alternative hypotheses, from Prof. Essa on YouTube .

Encyclopedia Britannica. Scientific Hypothesis. Jan. 13, 2022. https://www.britannica.com/science/scientific-hypothesis

Karl Popper, "The Logic of Scientific Discovery," Routledge, 1959.

California State University, Bakersfield, "Formatting a testable hypothesis." https://www.csub.edu/~ddodenhoff/Bio100/Bio100sp04/formattingahypothesis.htm  

Karl Popper, "Conjectures and Refutations," Routledge, 1963.

Price, P., Jhangiani, R., & Chiang, I., "Research Methods of Psychology — 2nd Canadian Edition," BCcampus, 2015.‌

University of Miami, "The Scientific Method" http://www.bio.miami.edu/dana/161/evolution/161app1_scimethod.pdf  

William M.K. Trochim, "Research Methods Knowledge Base," https://conjointly.com/kb/hypotheses-explained/  

University of California, Berkeley, "Multiple Hypothesis Testing and False Discovery Rate" https://www.stat.berkeley.edu/~hhuang/STAT141/Lecture-FDR.pdf  

University of California, Berkeley, "Science at multiple levels" https://undsci.berkeley.edu/article/0_0_0/howscienceworks_19

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Science Hypothesis

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Hypothesis are the bedrock of scientific investigation, guiding researchers toward understanding the unknown. Crafting effective science hypotheses involves precise formulation and prediction. This hypothesis statement guide delves into the intricacies of constructing science hypothesis statements, offering practical examples and valuable tips to ensure your hypothesis stand strong against the rigors of experimentation and analysis.

What is Science Hypothesis? – Definition

A science hypothesis is a proposed explanation or educated guess that can be tested through experimentation or observation. It serves as a preliminary assumption or prediction about a phenomenon, often derived from existing knowledge or theories. Science hypotheses are essential for guiding research and helping scientists investigate the validity of their predictions.

What is an example of a hypothesis statement in science?

Example of a hypothesis statement in science: “If the temperature of water increases, then the rate of plant growth will also increase.” This hypothesis predicts a cause-and-effect relationship between water temperature and plant growth, which can be tested through controlled experiments.

100 Science Hypothesis Statement Examples

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Science hypotheses lay the foundation for empirical exploration. These Thesis statements predict outcomes based on existing knowledge and guide research. Explore a variety of science hypothesis examples across different disciplines, showcasing the diverse ways scientists propose, test, and validate their assumptions. From physics to biology, chemistry to astronomy, delve into these examples that highlight the essence of scientific inquiry and discovery.

• Physics : If the mass of an object increases, its gravitational pull on another object will also increase.
• Biology : If plants are exposed to different light wavelengths, then the one exposed to red light will exhibit the highest growth rate.
• Chemistry : If the concentration of a reactant increases, then the rate of the chemical reaction will also increase.
• Astronomy : If the distance between two galaxies decreases, then their gravitational attraction will intensify.
• Geology : If the temperature of a rock sample increases, then its density will decrease due to expansion.
• Psychology : If individuals are exposed to positive affirmations, then their self-esteem scores will improve.
• Sociology : If economic inequality increases, then crime rates within a community will also rise.
• Environmental Science : If pollution levels decrease in a river, then the diversity of aquatic species will increase.
• Computer Science : If the processing speed of a computer chip increases, then the execution time of a software program will decrease.
• Meteorology : If atmospheric pressure drops significantly, then the likelihood of stormy weather conditions will rise.
• Neuroscience : If individuals engage in regular meditation, then their brain’s gray matter volume in regions associated with mindfulness will increase.
• Economics : If interest rates decrease, then consumer spending will rise due to increased borrowing.
• Anthropology : If a society’s cultural diversity increases, then its acceptance of differing norms and values will also grow.
• Zoology : If predators are introduced to an ecosystem, then the population of prey species will decline.
• Medical Research : If a new drug is administered, then patients with a specific medical condition will experience a reduction in symptoms.
• Nutrition Science : If individuals consume a diet high in antioxidants, then their risk of developing certain chronic diseases will decrease.
• Materials Science : If the temperature of a metal is lowered, then its electrical conductivity will decrease due to reduced kinetic energy.
• Political Science : If voter education initiatives increase, then voter turnout rates in elections will also rise.
• Geography : If urbanization expands in a region, then the average local temperature will increase due to the heat island effect.
• Ecology : If a keystone species is removed from an ecosystem, then the overall biodiversity of that ecosystem will be negatively impacted.
• Medieval History : If trade routes between two civilizations strengthen, then cultural exchange and technological advancements will flourish.
• Microbiology : If a specific bacterium is introduced to a microbial community, then it will outcompete other species for resources.
• Oceanography : If ocean temperatures rise, then coral reefs will experience bleaching due to the loss of symbiotic algae.
• Education : If class sizes are reduced, then student engagement and learning outcomes will improve.
• Genetics : If individuals inherit two recessive alleles for a particular trait, then they will exhibit the trait phenotypically.
• Criminology : If community policing initiatives are implemented, then the crime rate in neighborhoods will decrease due to improved trust between law enforcement and residents.
• Botany : If plants are exposed to varying levels of nutrients, then their growth rate and overall health will be affected accordingly.
• Epidemiology : If individuals are vaccinated against a specific virus, then the incidence of that virus in the population will decline.
• Architecture : If buildings are designed with energy-efficient features, then their energy consumption and environmental impact will be reduced.
• Literary Studies : If readers are exposed to diverse genres of literature, then their vocabulary and literary comprehension will expand.
• Mechanical Engineering : If the surface area of a heat exchanger is increased, then its efficiency in transferring thermal energy will improve.
• Artificial Intelligence : If a machine learning algorithm is trained on a larger dataset, then its accuracy in making predictions will increase.
• Sports Science : If athletes incorporate specific pre-game rituals, then their performance and focus during competitions will improve.
• Archaeology : If a new excavation site is discovered, then artifacts and evidence of past civilizations will be uncovered.
• Film Studies : If films use non-linear storytelling techniques, then audience engagement and interpretation will become more complex.
• Fashion Design : If clothing materials with better breathability are used, then wearers’ comfort levels in hot weather will increase.
• Music Psychology : If listeners are exposed to music with a fast tempo, then their heart rate and energy levels will be positively affected.
• Environmental Engineering : If a wastewater treatment system is upgraded, then the water quality of nearby rivers and streams will improve.
• Philosophy : If ethical dilemmas are discussed openly, then individuals’ moral reasoning and decision-making skills will become more refined.
• Cognitive Science : If individuals practice mindfulness meditation, then their attention span and cognitive control will enhance.
• Political Economy : If trade barriers between two countries are lifted, then their economic interdependence and cooperation will strengthen.
• Agricultural Science : If certain crops are rotated in a field, then soil fertility and nutrient content will be better maintained.
• Cultural Anthropology : If cultural norms change to value gender equality, then the division of labor and social roles will evolve accordingly.
• Linguistics : If a language’s phonetic structure is altered, then the perception and articulation of speech sounds will be affected.
• Religious Studies : If religious festivals are celebrated widely, then social cohesion and a sense of community among participants will increase.
• Urban Planning : If public transportation infrastructure is improved, then the use of private vehicles and traffic congestion will decrease.
• Renewable Energy : If solar panel efficiency increases, then the cost-effectiveness of solar energy as a power source will improve.
• Sustainable Agriculture : If organic farming practices are adopted, then soil health and biodiversity in agricultural fields will be enhanced.
• Human Genetics : If a specific gene mutation is present, then the likelihood of developing a hereditary disease will be higher.
• Space Exploration : If a spacecraft is sent to a distant planet, then the data collected will provide insights into its composition and environment.
• Cultural Studies : If a society values inclusivity in its media representations, then stereotypes and biases will be challenged.
• Quantum Physics : If two entangled particles are measured, then the measurement of one particle will instantaneously affect the state of the other particle, regardless of distance.
• Social Work : If support systems are established for individuals facing addiction, then their likelihood of successful recovery will increase.
• Civil Engineering : If a bridge is constructed using specific materials and design principles, then its load-bearing capacity and structural integrity will be maximized.
• Educational Technology : If interactive learning platforms are integrated into classrooms, then students’ engagement and retention of concepts will rise.
• Animal Behavior : If a specific stimulus is introduced to an animal’s environment, then its behavioral response will indicate whether the stimulus is perceived as positive or negative.
• Public Health : If a vaccination campaign targets a high percentage of the population, then the spread of a contagious disease will be curbed.
• Forensic Science : If DNA evidence is analyzed from a crime scene, then it can be matched to potential suspects or used to exonerate individuals.
• Game Design : If a game incorporates branching storylines, then players’ choices will lead to multiple possible outcomes and endings.
• Gender Studies : If gender stereotypes are challenged in educational settings, then students’ understanding of gender roles and identities will evolve.
• Particle Physics : If a new particle is discovered in particle accelerator experiments, then it may contribute to our understanding of fundamental forces.
• Culinary Science : If cooking techniques are adjusted, then the texture and flavor of a dish will be enhanced.
• Developmental Psychology : If children are exposed to early childhood education programs, then their cognitive and social development will be positively influenced.
• Journalism : If journalists provide unbiased coverage of events, then the public’s perception and understanding of news stories will be more accurate.
• Business Management : If a company implements remote work policies, then employees’ job satisfaction and productivity will be impacted.
• Astronomy : If a telescope observes a distant celestial object, then its light spectrum can reveal information about its composition and distance.
• Climate Science : If greenhouse gas emissions continue to rise, then global temperatures will increase, leading to more frequent and severe climate events.
• Molecular Biology : If a specific gene is mutated, then the protein it codes for may lose its function, leading to a genetic disorder.
• Urban Sociology : If urban planning focuses on mixed-use development, then neighborhoods will become more walkable and vibrant.
• Environmental Science : If deforestation continues in a particular region, then biodiversity loss and habitat destruction will result.
• Educational Psychology : If students receive constructive feedback, then their academic performance and self-esteem will improve.
• Sports Nutrition : If athletes consume a balanced diet, then their energy levels and physical performance will be optimized.
• Industrial Engineering : If a manufacturing process is streamlined, then production efficiency and cost-effectiveness will increase.
• Climate Change Mitigation : If renewable energy sources replace fossil fuels, then carbon emissions and air pollution will decrease.
• Criminal Justice : If restorative justice programs are implemented, then recidivism rates among offenders will decrease.
• Cognitive Neuroscience : If brain imaging techniques are used, then neural activity patterns associated with memory retrieval can be identified.
• Environmental Policy : If conservation policies are enforced, then endangered species populations will have a chance to recover.
• Tourism Management : If sustainable tourism practices are adopted, then the negative impact of tourism on local ecosystems will be minimized.
• Public Opinion Research : If surveys are conducted on political preferences, then insights into voter behavior and attitudes can be gained.
• Sociolinguistics : If language use changes over time, then linguistic patterns and dialects in a community may evolve.
• Consumer Behavior : If marketing strategies incorporate social media influencers, then consumer purchasing decisions will be influenced.
• Digital Communication : If online privacy measures are strengthened, then users’ data security and trust in digital platforms will increase.
• Cancer Research : If a specific genetic mutation is identified, then targeted therapies can be developed to treat the cancer associated with that mutation.
• Human Rights Advocacy : If educational campaigns raise awareness about human rights violations, then public pressure on governments to address these issues will rise.
• Educational Assessment : If standardized tests are redesigned to focus on critical thinking skills, then students’ analytical abilities will be better evaluated.
• Epidemiology : If a specific virus spreads within a community, then the rate of infection and transmission can be studied to develop effective containment strategies.
• Cognitive Psychology : If memory recall is examined under different conditions, then the factors influencing memory retrieval can be identified.
• Financial Economics : If interest rates are lowered by the central bank, then borrowing costs for businesses and individuals will decrease.
• Marine Biology : If ocean temperatures rise due to climate change, then coral bleaching events will become more frequent, leading to coral reef degradation.
• Political Science : If voter turnout is influenced by campaign advertising, then the correlation between media exposure and voting behavior can be analyzed.
• Clinical Psychology : If cognitive-behavioral therapy is administered to individuals with anxiety disorders, then their symptoms will show a reduction.
• Public Policy : If a government enforces stricter regulations on smoking in public spaces, then the prevalence of smoking-related health issues will decline.
• Material Science : If a new material is developed with specific properties, then its potential applications in various industries can be explored.
• Language Acquisition : If children are exposed to multiple languages in their early years, then their linguistic skills may develop differently compared to monolingual children.
• Tourism Economics : If travel restrictions are lifted, then the recovery of the tourism industry and its contribution to the local economy can be assessed.
• Behavioral Economics : If individuals are given incentives to make environmentally friendly choices, then the impact of economic incentives on behavior can be studied.
• Educational Technology : If online learning platforms are used in classrooms, then their effect on student engagement and academic performance can be evaluated.
• Health Policy : If universal healthcare coverage is implemented, then access to medical services and health outcomes for the population can be improved.
• Agricultural Economics : If crop yields are compared between traditional farming methods and modern agricultural practices, then the efficiency of different approaches can be determined.
• Literary Analysis : If a specific theme is analyzed across different literary works, then the ways in which authors address and convey that theme can be explored.

Science Hypothesis Statement Examples for Psychology

These psychology hypothesis pertain to human behaviors, emotions, or cognitive processes. They are tailored to the field of psychology, which studies the human mind and behavior. For instance, “Effects of Sleep on Memory” posits a connection between sleep duration and memory performance.

• Effects of Sleep on Memory : People who sleep 8 hours per night will perform better on memory tests compared to those who sleep only 4 hours.
• Role of Colors in Mood Regulation : Exposure to blue light will decrease feelings of sadness in depressed individuals.
• Childhood Attachment and Adult Relationships : Individuals with secure childhood attachments will have more stable romantic relationships in adulthood.
• Influence of Music on Productivity : Listening to classical music while working increases task completion rates among office workers.
• Gaming and Reaction Time : Regular gamers will have quicker reaction times than non-gamers in response to unexpected stimuli.
• Effects of Meditation on Stress : Individuals who practice daily meditation will report lower stress levels compared to those who don’t meditate.
• Social Media Usage and Loneliness : High usage of social media correlates with increased feelings of loneliness in teenagers.
• Class Size and Student Performance : Students in smaller class sizes will score higher on standardized tests than students in larger class sizes.
• Scent and Memory Recall : People exposed to a specific scent during learning will recall information better when the same scent is present during retrieval.
• Financial Incentives and Motivation : Providing financial incentives will increase motivation for completing mundane tasks.

Simple Science Hypothesis Statement Examples

These are basic and straightforward scientific hypotheses that cover various fields, such as biology or physics. They’re easy to understand even for people without much scientific background. For instance, the simple hypothesis tatement about “Plant Growth” directly relates the use of fertilizer to plant height.

• Plant Growth : Adding fertilizer will make plants grow taller.
• Solar Energy : Increasing sunlight exposure will increase the voltage output of a solar cell.
• Density : Objects made of metal will sink in water.
• Digestion : Enzyme supplements will increase the speed of food digestion.
• Osmosis : Potatoes placed in salt water will shrink due to loss of water.
• Evaporation : Water will evaporate faster on a hot day compared to a cold day.
• Nutrition : Plants given sugar water will develop yellow leaves.
• Magnetism : Increasing the temperature of a magnet will decrease its magnetic strength.
• Conduction : Metals will conduct electricity better than plastics.
• Reflection : Shiny surfaces reflect more light than dull surfaces.

Strong Science Hypothesis Statement Examples

These are more detailed and specific hypotheses, often relating to a well-defined scientific question. They may also suggest a precise outcome or relationship. For example, “Vaccination and Immunity” indicates a specific result (production of specific antibodies) in response to a defined action (vaccinating mice).

• Environmental Toxins and Cell Growth : Exposure to specific environmental toxins will inhibit the division of cells in an organism.
• Nutrition and Cognitive Performance : Diets rich in omega-3 fatty acids will significantly enhance cognitive performance in adults over 60.
• Genetic Mutations and Disease Resistance : Specific genetic mutations in fruit flies will confer resistance to a particular pesticide.
• Neurotransmitters and Behavior : An increase in serotonin levels in the brain will lead to a decrease in aggressive behaviors in rats.
• Plant Pathogens and Resistance : Tomato plants genetically modified to express the XYZ gene will resist infection from the ABC pathogen more effectively than non-modified plants.
• Vaccination and Immunity : Vaccinating mice with a particular strain of virus will lead to the production of specific antibodies that prevent future infections.
• Hormonal Levels and Bone Density : Post-menopausal women with decreased estrogen levels will have a significant reduction in bone density compared to pre-menopausal women.
• Enzyme Concentration and Reaction Rate : Doubling the concentration of an enzyme in a solution will double the rate of the substrate’s conversion to the product.
• Climate Change and Coral Bleaching : An increase in sea surface temperature by 2°C will lead to a 50% increase in coral bleaching events.
• Pesticides and Pollinator Health : Exposure to the pesticide DEF will reduce the foraging ability of honeybees by at least 30%.

Scientific Hypothesis Statement Examples

These are broader scientific hypothesis applicable to different scientific disciplines. They’re structured to make clear, testable predictions about the relationship between variables. “Bacterial Growth,” for instance, predicts the outcome of bacteria exposed to UV light.

• Bacterial Growth : Bacteria exposed to ultraviolet (UV) light will have a reduced growth rate compared to those not exposed to UV light.
• Antibiotic Resistance : Overuse of antibiotics in livestock will lead to an increase in antibiotic-resistant bacteria in humans.
• Evolutionary Adaptation : Birds with longer beaks will have an advantage in accessing food after a drastic environmental change.
• Photosynthesis Rate : Plants grown under red light will have a lower rate of photosynthesis compared to those grown under blue light.
• Stem Cell Differentiation : The presence of growth factor X will guide stem cells to differentiate into nerve cells more frequently than muscle cells.
• Ozone Layer and UV Radiation : Depletion of the ozone layer will result in increased UV radiation levels on Earth’s surface.
• Protein Folding : Mutation at position 123 in protein Z will lead to a misfolded protein structure.
• Water Quality and Fish Health : Rivers with high levels of industrial pollutants will have a reduced fish population due to compromised gill functionality.
• Seismic Activity and Plate Tectonics : Regions located at the boundaries of tectonic plates will experience more frequent and stronger earthquakes.
• Drug Efficacy : Patients treated with drug Y will recover from infection twice as fast as those treated with a placebo.

Alternative Hypothesis Statement Examples for Science

The alternative hypothesis states that there is a statistically significant relationship between two variables. It’s what you might want to prove or demonstrate. For example, the hypothesis about “Green Tea and Metabolism” suggests that drinking green tea can have a positive effect on metabolic rates.

• Dietary Supplements and Energy Levels : Consuming a daily vitamin B12 supplement will increase energy levels in vegans.
• Soil Type and Crop Yield : Sandy soil will produce a lower maize yield than loamy soil.
• Air Pollution and Respiratory Diseases : Living in areas with higher particulate matter (PM2.5) levels will increase the incidence of respiratory diseases.
• Green Tea and Metabolism : Drinking green tea daily will increase metabolic rates in adults.
• Exercise and Brain Health : Engaging in regular aerobic exercise will increase cognitive function in older adults.
• Artificial Sweeteners and Appetite : Consuming artificial sweeteners will increase appetite in individuals.
• Forest Density and Wildlife Diversity : Forests with higher tree density will support a more diverse range of wildlife.
• Hydration and Skin Health : Drinking at least 2 liters of water daily will improve skin elasticity.
• Biofuels and Engine Performance : Engines running on biofuel will have a higher fuel efficiency than those running on traditional petroleum fuels.
• Artificial Light and Plant Growth : Plants grown under LED lights will have a faster growth rate than those grown under fluorescent lights.

Null Hypothesis Statement Examples for Science

The null hypothesis posits that there is no relationship between two variables. It’s the statement you want to test against. Scientists often set out to reject the null hypothesis to demonstrate there’s a relationship. For instance, “Diet and Weight Loss” asserts there’s no difference in weight loss outcomes between two diet types.

• Diet and Weight Loss : There is no difference in weight loss between individuals on a low-carb diet and those on a low-fat diet.
• Antibacterial Soap and Hand Hygiene : Using antibacterial soap does not decrease the number of bacteria on hands compared to using regular soap.
• Meditation and Blood Pressure : There is no difference in blood pressure levels between individuals who meditate daily and those who don’t.
• Organic Foods and Nutrient Content : Organic fruits and vegetables have the same nutrient content as non-organic fruits and vegetables.
• Pain Relievers and Pain Reduction : Over-the-counter pain reliever X does not reduce pain more effectively than a placebo.
• Educational Method and Learning : There is no difference in learning outcomes between students taught using method A and those taught using method B.
• Herbal Treatment and Sleep Duration : Herbal treatment Y does not increase sleep duration compared to a placebo.
• Sunscreen and Sunburn : There is no difference in sunburn incidence between individuals using sunscreen with SPF 30 and those using sunscreen with SPF 50.
• Caffeine and Alertness : Consuming caffeine does not increase alertness levels compared to not consuming caffeine.
• Probiotics and Gut Health : Taking daily probiotics does not increase the diversity of gut bacteria compared to not taking probiotics.

What is a good hypothesis for a science project?

A good hypothesis is a fundamental cornerstone for any scientific project. It provides direction for your research, helping you to focus your investigations and understand the potential outcomes. Here’s what characterizes a good hypothesis:

• Testable : A good hypothesis must be something that can be supported or refuted through experimentation, observation, or analysis.
• Clear and Concise : It should be straightforward and to the point, making it easier for you or others to test.
• Logical : It should make logical sense, building upon existing knowledge and literature.
• Specific : The hypothesis should clearly identify the variables and the relationship between them.
• Relevant : It should be pertinent to the subject matter and not diverge into unrelated areas.
• Predictive : It should make a clear prediction about what you expect to happen in your study.

How do you write a scientific hypothesis statement? – A Step by Step Guide

• Identify Your Research Question : Before you can draft a hypothesis, you need to determine what you’re trying to answer. For example, “Does the type of soil affect plant growth?”
• Perform Preliminary Research : Understand existing literature on the topic. This will help ensure that your hypothesis is original and rooted in current understanding.
• Independent Variable (what you change): e.g., type of soil.
• Dependent Variable (what you measure): e.g., plant growth.
• Make a Prediction : Based on your research, predict the relationship between your variables.
• If : Describes the change or treatment (independent variable).
• Then : Predicts the outcome (dependent variable).
• Because : Provides a rationale based on your background research. E.g., “If a plant is grown in sandy soil, then it will grow slower than in loamy soil, because sandy soil retains less water.”
• Keep it Simple : Avoid complex sentences or jargon. Your hypothesis should be understandable even to someone not in your field.
• Review and Revise : Once drafted, revisit your hypothesis. Ensure it aligns with your research question and that it remains clear and testable.

Tips for Writing Science Hypothesis

• Start with Curiosity : Your initial question should stem from genuine curiosity. It might begin as a broad query which you then refine.
• Use Open-Ended Questions : Start your question with words like “How,” “What,” or “Why.” These types of questions don’t presuppose an answer and lead to more in-depth investigation.
• One Variable at a Time : Especially for beginner projects, limit your hypothesis to one independent variable to keep your study focused and manageable.
• Avoid Biased Language : Your hypothesis should not show any personal biases. Instead of “I believe” or “I think,” use neutral terms.
• Stay Relevant to Available Tools and Resources : Ensure that you can test your hypothesis with the tools, time, and resources available to you.
• Peer Review : Before finalizing your question and hypothesis, have a peer or mentor review it. They might catch ambiguities or complexities you missed.
• Be Ready to Accept Any Outcome : A common mistake is becoming too attached to proving your hypothesis right. Remember, disproving a hypothesis can be just as valuable as proving it.

By carefully crafting your research question and hypothesis, you’ll set a solid foundation for your science project. Whether your results support or challenge your initial predictions, you’ll contribute to the vast and ever-growing body of scientific knowledge.

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70 Best High School Science Fair Projects in Every Subject

Fire up the Bunsen burners!

For even more free science ideas and printables,  head to our science hub!  You’ll find resources in every science subject for middle and high school.

The cool thing about high school science fair projects is that kids are old enough to tackle some pretty amazing concepts. Some science experiments for high school are just advanced versions of simpler projects they did when they were younger, with detailed calculations or fewer instructions. Other projects involve fire, chemicals, or other materials they weren’t old enough to use before.

Note: Many of these projects can be used as classroom labs as well as science fair projects. Feel free to adapt them as needed for your students’ individual projects, or use them as full-class activities every student will enjoy. However you plan to use the projects, just consider variables that you can change up, like materials or other parameters.

To make it easier to find the right high school science fair project idea for you, we’ve rated all the projects by difficulty and the materials needed:

Difficulty:

• Easy: Low or no-prep experiments you can do pretty much anytime
• Medium: These take a little more setup or a longer time to complete
• Advanced: Experiments like these take a fairly big commitment of time or effort
• Basic: Simple items you probably already have around the house
• Medium: Items that you might not already have but are easy to get your hands on
• Advanced: These require specialized or more expensive supplies to complete

Biology and Life Sciences High School Science Fair Projects

Chemistry high school science fair projects, physics high school science fair projects, engineering high school stem fair projects.

Explore the living world with these biology science project ideas, learning more about plants, animals, the environment, and much more.

FEATURED PICK

Ward’s Science Engage Kit : Cell Cycles

Difficulty: Medium / Materials: Easy (Everything is provided for you!)

In this activity, your students will step into the shoes of an R&D intern at an agricultural biotech company. They’ll dig into a new plant crop virus and brainstorm solutions to tackle it.

Ward’s Science Engage Kits are an amazing way to bring more inquiry-based activities into your classroom. The kits come with everything you need to complete hands-on labs with your class. Your students will develop their critical questioning, research, and teamwork skills while working to solve problems that feel real and important.

Extract DNA from an onion

Difficulty: Medium / Materials: Medium

You don’t need a lot of supplies to perform this experiment, but it’s impressive nonetheless. Turn this into a science fair project by trying it with other fruits and vegetables too.

Make plants move with light

By this age, kids know that many plants move toward sunlight, a process known as phototropism. So high school science fair projects on this topic need to introduce variables into the process, like covering seedling parts with different materials to see the effects.

Test the 5-second rule

We’d all like to know the answer to this one: Is it really safe to eat food you’ve dropped on the floor? Design and conduct an experiment to find out (although we think we might already know the answer).

Find out if color affects taste

Just how interlinked are all our senses? Does the sight of food affect how it tastes? Find out with a fun food science fair project like this one!

See the effects of antibiotics on bacteria

Difficulty: Medium / Materials: Advanced

Bacteria can be divided into two groups: gram-positive and gram-negative. In this experiment, students first determine the two groups, then try the effects of various antibiotics on them. You can get a gram stain kit , bacillus cereus and rhodospirillum rubrum cultures, and antibiotic discs from Home Science Tools.

Learn more: Antibiotics Project

Witness the carbon cycle in action

Experiment with the effects of light on the carbon cycle. Make this science fair project even more interesting by adding some small aquatic animals like snails or fish into the mix.

Learn more: Carbon Cycle

Look for cell mitosis in an onion

Cell mitosis (division) is actually easy to see in action when you look at onion root tips under a microscope. Students will be amazed to see science theory become science reality right before their eyes. Adapt this lab into a high school science fair project by applying the process to other organisms too.

Test the effects of disinfectants

Grow bacteria in a petri dish along with paper disks soaked in various antiseptics and disinfectants. You’ll be able to see which ones effectively inhibit bacteria growth.

Learn more: Effectiveness of Antiseptics and Disinfectants

Re-create Mendel’s pea plant experiment

Gregor Mendel’s pea plant experiments were some of the first to explore inherited traits and genetics. Try your own cross-pollination experiments with fast-growing plants like peas or beans.

Pit hydroponics against soil

Growing vegetables without soil (hydroponics) is a popular trend that allows people to garden just about anywhere.

More Life Sciences and Biology Science Fair Projects for High School

Use these questions and ideas to design your own experiment:

• Explore ways to prevent soil erosion.
• What are the most accurate methods of predicting various weather patterns?
• Try out various fertilization methods to find the best and safest way to increase crop yield.
• What’s the best way to prevent mold growth on food for long-term storage?
• Does exposure to smoke or other air pollutants affect plant growth?
• Compare the chemical and/or bacterial content of various water sources (bottled, tap, spring, well water, etc.).
• Explore ways to clean up after an oil spill on land or water.
• Conduct a wildlife field survey in a given area and compare it to results from previous surveys.
• Find a new use for plastic bottles or bags to keep them out of landfills.
• Devise a way to desalinate seawater and make it safe to drink.

Bunsen burners, beakers and test tubes, and the possibility of (controlled) explosions? No wonder chemistry is such a popular topic for high school science fair projects!

Break apart covalent bonds

Break the covalent bond of H 2 O into H and O with this simple experiment. You only need simple supplies for this one. Turn it into a science fair project by changing up the variables—does the temperature of the water matter? What happens if you try this with other liquids?

Learn more: Covalent Bonds

Measure the calories in various foods

Are the calorie counts on your favorite snacks accurate? Build your own calorimeter and find out! This kit from Home Science Tools has all the supplies you’ll need.

Detect latent fingerprints

Forensic science is engrossing and can lead to important career opportunities too. Explore the chemistry needed to detect latent (invisible) fingerprints, just like they do for crime scenes!

Learn more: Fingerprints Project

Use Alka-Seltzer to explore reaction rate

Difficulty: Easy / Materials: Easy

Tweak this basic concept to create a variety of high school chemistry science fair projects. Change the temperature, surface area, pressure, and more to see how reaction rates change.

Determine whether sports drinks provide more electrolytes than OJ

Are those pricey sports drinks really worth it? Try this experiment to find out. You’ll need some special equipment for this one; buy a complete kit at Home Science Tools .

Turn flames into a rainbow

You’ll need to get your hands on a few different chemicals for this experiment, but the wow factor will make it worth the effort! Make it a science project by seeing if different materials, air temperature, or other factors change the results.

Discover the size of a mole

The mole is a key concept in chemistry, so it’s important to ensure students really understand it. This experiment uses simple materials like salt and chalk to make an abstract concept more concrete. Make it a project by applying the same procedure to a variety of substances, or determining whether outside variables have an effect on the results.

Learn more: How Big Is a Mole?

Cook up candy to learn mole and molecule calculations

This edible experiment lets students make their own peppermint hard candy while they calculate mass, moles, molecules, and formula weights. Tweak the formulas to create different types of candy and make this into a sweet science fair project!

Learn more: Candy Chemistry

Make soap to understand saponification

Take a closer look at an everyday item: soap! Use oils and other ingredients to make your own soap, learning about esters and saponification. Tinker with the formula to find one that fits a particular set of parameters.

Learn more: Saponification

Uncover the secrets of evaporation

Explore the factors that affect evaporation, then come up with ways to slow them down or speed them up for a simple science fair project.

Learn more: Evaporation

More Chemistry Science Fair Projects for High School

These questions and ideas can spark ideas for a unique experiment:

• Compare the properties of sugar and artificial sweeteners.
• Explore the impact of temperature, concentration, and seeding on crystal growth.
• Test various antacids on the market to find the most effective product.
• What is the optimum temperature for yeast production when baking bread from scratch?
• Compare the vitamin C content of various fruits and vegetables.
• How does temperature affect enzyme-catalyzed reactions?
• Investigate the effects of pH on an acid-base chemical reaction.
• Devise a new natural way to test pH levels (such as cabbage leaves).
• What’s the best way to slow down metal oxidation (form of rust)?
• How do changes in ingredients and method affect the results of a baking recipe?

When you think of physics science projects for high school, the first thing that comes to mind is probably the classic build-a-bridge. But there are plenty of other ways for teens to get hands-on with physics concepts. Here are some to try.

Remove the air in a DIY vacuum chamber

You can use a vacuum chamber to do lots of cool high school science fair projects, but a ready-made one can be expensive. Try this project to make your own with basic supplies.

Learn more: Vacuum Chamber

Put together a mini Tesla coil

Looking for a simple but showy high school science fair project? Build your own mini Tesla coil and wow the crowd!

Boil water in a paper cup

Logic tells us we shouldn’t set a paper cup over a heat source, right? Yet it’s actually possible to boil water in a paper cup without burning the cup up! Learn about heat transfer and thermal conductivity with this experiment. Go deeper by trying other liquids like honey to see what happens.

Build a better light bulb

Emulate Thomas Edison and build your own simple light bulb. You can turn this into a science fair project by experimenting with different types of materials for filaments.

Measure the speed of light—with your microwave

Grab an egg and head to your microwave for this surprisingly simple experiment. By measuring the distance between cooked portions of egg whites, you’ll be able to calculate the wavelength of the microwaves in your oven and, in turn, the speed of light.

Generate a Lichtenberg figure

See electricity in action when you generate and capture a Lichtenberg figure with polyethylene sheets, wood, or even acrylic and toner. Change the electrical intensity and materials to see what types of patterns you can create.

Learn more: Lichtenberg Figure

Explore the power of friction with sticky-note pads

Difficulty: Medium / Materials: Basic

Ever try to pull a piece of paper out of the middle of a big stack? It’s harder than you’d think! That’s due to the power of friction. In this experiment, students interleave the sheets of two sticky-note pads, then measure how much weight it takes to pull them apart. The results are astonishing!

Build a cloud chamber to prove background radiation

Ready to dip your toe into particle physics? Learn about background radiation and build a cloud chamber to prove the existence of muons.

Measure the effect of temperature on resistance

This is a popular and classic science fair experiment in physics. You’ll need a few specialized supplies, but they’re pretty easy to find.

Learn more: Effect of Temperature on Resistance

Launch the best bottle rocket

A basic bottle rocket is pretty easy to build, but it opens the door to lots of different science fair projects. Design a powerful launcher, alter the rocket so it flies higher or farther, or use only recycled materials for your flyer.

More Physics Science Fair Projects for High School

Design your own experiment in response to these questions and prompts.

• Determine the most efficient solar panel design and placement.
• What’s the best way to eliminate friction between two objects?
• Explore the best methods of insulating an object against heat loss.
• What effect does temperature have on batteries when stored for long periods of time?
• Test the effects of magnets or electromagnetic fields on plants or other living organisms.
• Determine the best angle and speed of a bat swing in baseball.
• What’s the best way to soundproof an area or reduce noise produced by an item?
• Explore methods for reducing air resistance in automotive design.
• Use the concepts of torque and rotation to perfect a golf swing.
• Compare the strength and durability of various building materials.

Many schools are changing up their science fairs to STEM fairs to encourage students with an interest in engineering to participate. Many great engineering science fair projects start with a STEM challenge, like those shown here. Use these ideas to spark a full-blown project to build something new and amazing!

Construct a model maglev train

Maglev trains may just be the future of mass transportation. Build a model at home, and explore ways to implement the technology on a wider basis.

Learn more: Maglev Model Train

Design a more efficient wind turbine

Wind energy is renewable, making it a good solution for the fossil fuel problem. For a smart science fair project, experiment to find the most efficient wind turbine design for a given situation.

Re-create Da Vinci’s flying machine

Da Vinci sketched several models of “flying machines” and hoped to soar through the sky. Do some research into his models and try to reconstruct one of your own.

Learn more: Da Vinci Flying Machine

Design a heart-rate monitor

Smartwatches are ubiquitous these days, so pretty much anyone can wear a heart-rate monitor on their wrist. But do they work any better than one you can build yourself? Get the specialized items you need like the Arduino LilyPad Board on Amazon.

Race 3D printed cars

3D printers are a marvel of the modern era, and budding engineers should definitely learn to use them. Use Tinkercad or a similar program to design and print race cars that can support a defined weight, then see which can roll the fastest! (No 3D printer in your STEM lab? Check the local library. Many of them have 3D printers available for patrons to use.)

Learn more: 3D Printed STEM Racers

Grow veggies in a hydroponic garden

Hydroponics is the gardening wave of the future, making it easy to grow plants anywhere with minimal soil required. For a science fair STEM engineering challenge, design and construct your own hydroponic garden capable of growing vegetables to feed a family. This model is just one possible option.

Learn more: Vertical Hydroponic Farm

Grab items with a mechanical claw

Delve into robotics with this engineering project. This kit includes all the materials you need, with complete video instructions. Once you’ve built the basic structure, tinker around with the design to improve its strength, accuracy, or other traits.

Buy it: Hydraulic Claw

Construct a crystal radio

Return to the good old days and build a radio from scratch. This makes a cool science fair project if you experiment with different types of materials for the antenna. It takes some specialized equipment, but fortunately, Home Science Tools has an all-in-one kit for this project.

Learn more: Crystal Radio

Build a burglar alarm

The challenge? Set up a system to alert you when someone has broken into your house or classroom. This can take any form students can dream up, and you can customize this STEM high school science experiment for multiple skill levels. Keep it simple with an alarm that makes a sound that can be heard from a specified distance. Or kick it up a notch and require the alarm system to send a notification to a cell phone, like the project at the link.

Learn more: Intruder Alarm

Walk across a plastic bottle bridge

Balsa wood bridges are OK, but this plastic bottle bridge is really impressive! In fact, students can build all sorts of structures using the concept detailed at the link. It’s the ultimate upcycled STEM challenge!

Learn more: TrussFab Structures

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VanCleave's Science Fun

Your Guide to Science Projects, Fun Experiments, and Science Research

Science Project: Slime/Hypothesis

By Janice VanCleave

A hypothesis is your guess about the answer to the project question. This is not a “wild” guess. You need to have a good reason for the hypothesis you state.

Project Question

1. If two solution, glue and borax, are mixed, what effect would the viscosity of the  glue used have on the viscosity of the slime ?

independent variable: viscosity of glue

dependent variable: viscosity of slime

Project Hypothesis

1. Viscosity measures how easy something flows. Glues that are thick and slow to flow will produce thick, slow flowing slime.

2. Viscosity is the resistance to flowing, so the more viscous the glue the more viscous will be the slime.

Step 6 : Experiment

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