• Ask a question
  • Gather information and observe (research)
  • Make a hypothesis (guess the answer)
  • Experiment and test your hypothesis
  • Analyze your test results
  • Modify your hypothesis, if necessary
  • Present a conclusion
  • Retest (often done by other scientists)

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The Scientific Method Lesson Plan: Developing Hypotheses

Submitted by: charlie conway.

This is a lesson plan designed to be incorporated into a elementary or middle school general science class. Using BrainPOP and its resources, students will be introduced (or further exposed) to the steps necessary to undertake scientific experimentation leading (perhaps) to a Science Fair project. The Scientific Method is a core structure in learning about scientific inquiry, and although there are many variations of this set of procedures, they all usually have similar components. This lesson should take 45-60 minutes, with opportunities for extending the lesson further.

Students will:

  • Students will use BrainPOP features to build their understandings of the Scientific Method.
  • Students will learn how to identify and write effective hypotheses.
  • Students will use game play to write an appropriate hypothesis for an experiment.
  • Students will identify and utilize the tools necessary to design a scientific investigation.
  • Laptops/Computers
  • Interactive White Board
  • Pencil/Paper
  • Class set of photocopies of the Scientific Method Flow Chart
  • BrainPOP accounts (optional)



These procedures may be modified according to the needs/resources of each teacher & class. For example, you may decide to do the quiz with pencil/paper, or do the quiz as a class.

Lesson Procedure:

  • Ask the students how scientists answer questions and solve problems. Take a few minutes to explore students' prior knowledge with a short discussion.
  • Tell the class that you're going to watch a BrainPOP movie about answering a scientific question about plant growth.
  • Show the BrainPOP movie on the Scientific Method two times. The first time, students should just watch and listen. The second time they should take notes. Pause the movie at critical STOP points.
  • Students should log on to their individual student accounts and take the Scientific Method Quiz to give the teacher some immediate feedback. (This can also be done as a pre-assessment, or at the very end of the lesson). NOTE: If you choose to, you can give a pencil/paper quiz also; students who work best with electronic media can be given accommodations). If you don't have access to individual student logins via MyBrainPOP (a school subscription), students can take the Review Quiz or paper quiz instead.
  • Discuss the main points from the movie: a. Write the definition of the scientific method: the procedure scientists use to help explain why things happen. b. Make a list on the board of the steps mentioned as part of the scientific method: problem, fact finding, observation, inference, hypothesis, experiment, conclusions. c. Tell students that there are various versions of the scientific method that they may see, but they are all basically the same.
  • Hand out the Scientific Method Flow Chart . Introduce the "If...then...because..." format for writing hypotheses. Give the students 10 minutes to complete the sheet with their group. They may use their notes from the movie to help them, and/or work collaboratively with other students.
  • Discuss some of the student responses in class. Focus on the hypotheses, and explain that a good hypothesis is a testable explanation of the problem. For example, a good hypothesis to the third problem would be, "If I move farther away from the microwave oven, then the cell phone signal will improve because I am further away from the source of interference." Show how this is a TESTABLE hypothesis that can lead to a scientific experiment.
  • Introduce the students to the Pavlov’s Dog game in GameUP. Allow time for the kids to explore the game without telling them why they are playing it.
  • After 10-15 minutes, have the students take a break from playing, and have a short discussion about the game. Ask if anyone was able to complete the task successfully, and have them share how they got the "diploma." If time allows, show the students how to complete the task so that they all understand that the dog has been conditioned to respond to a stimulus (noise before food has been introduced).
  • Have the students write a hypothesis that Pavlov may have written before he started his experiment. Students can either do this with pencil/paper, or the teacher may create a BrainPOP quiz and have students submit their hypothesis electronically. This may be used as a part of the assessment.
  • Choose some sample responses from the students, highlighting the hypotheses that are TESTABLE, and not just guesses or predictions.

If this lesson is an introduction to allowing students to plan and carry out their own experiments, then all that follows is naturally an extension to the lesson.

Other, shorter extensions are easy to develop as well.

Extension Activities:

hypothesis definition science 4th grade

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Developing a Hypothesis

Two girls exploring plant life in the woods

Two girls exploring plant life in the woods (Christine Glade, iStockphoto)

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Learn what makes a good hypothesis, and how to develop one.

Developing a Scientific Hypothesis

After identifying a  testable question , it is important for students to research and or/review what they already know about the scientific principles involved in their experimental inquiries. After that, and before conducting the inquiry through testing and observation, students need to develop a scientific  hypothesis .

Is a hypothesis the same as a guess?

The short answer is no! Anyone can make a guess about anything. Guesses are not generally based on knowledge, but rather are rough estimates that people give when they don’t know the answer to a question. A scientific hypothesis, on the other hand, is not only based on prior knowledge and experiences but also on known factual information obtained through research.

Misconception Alert Like making an estimate in math, a hypothesis should be written before doing an inquiry, not after!

Is a hypothesis the same as a prediction? 

Again, the answer is no, although the distinction between these two terms is not always clear. A  prediction  is an estimate or forecast about something that might happen or the way that something will be based on prior knowledge and experience and known facts (e.g., I predict it will rain tomorrow, I predict that my plant will have two seed leaves, etc.).

Rainy day

Shown is a colour photograph of a boat near a beach in the rain. The camera lens is sprinkled with rain drops. These are in sharp focus, in the foreground. Most of the rest of the photograph is out of focus in the background.  There is a strip of dark green grass along the bottom of the frame. Above that is a strip of beige sand. The water is shaded from light grey at the bottom to medium grey at the top. A dark green hill rises up behind the water, to the left. The sky is mottled with grey, white and blueish grey clouds. A small, yellow wooden rowboat is in sharp focus. It is moored to the shore with a white rope, next to a round, orange float.

Like a prediction, a hypothesis forecasts what might happen, but a hypothesis goes beyond a prediction. It includes not only what might happen, but why something might happen. In other words, it explains the relationship between variables. The most significant difference between a prediction and an hypothesis is that a hypothesis is intended to lead to a testable investigation, whereas a prediction is not.

To put it in a different way, a prediction is an estimate of an end result (e.g., I predict that the plant will be tall) whereas a hypothesis is a statement that attempts to explain a phenomena by relating cause and effect (e.g., if we give plants more water, then they will grow taller).

Watering a plant in a window box

Shown is a colour photograph of water falling from a blue watering can onto a pink flowering plant.  The frame is filled with green foliage. In the background, out of focus, is a row of pink, flowering plants in boxes along a wooden railing. In the foreground, a gloved hand tips a large, cornflower blue watering can over the first plant.

Misconception Alert Not every inquiry lends itself to the testing of a hypothesis. Many inquiries involve research questions that ask if relationships exist among variables or involve situations where testing is not possible, such as population inquiries, historical inquiries, etc. For example, you could never test a hypothesis about which type of food a given dinosaur preferred to eat!

Toy dinosaurs with a broccoli floret

Shown is a colour photograph of miniature plastic dinosaurs gathered around a piece of broccoli that resembles a tree.  A piece of broccoli stands upright in the middle of the photograph. It has a long, pale green stem and a full, dark green floret. It looks like a green tree with branches and tiny leaves. Five toy dinosaurs have been placed around the broccoli so they look like they're snacking it. They are a little bit shorter than the broccoli, so their mouths reach the bushiest parts of it.  The dinosaur in the foreground is dark reddish brown with scaly-looking skin and tiny arms. Behind it, a dark green dinosaur with a long neck stretches to the low branches. In the background, a dark brown triceratops looks on. The long neck of a black dinosaur reaches in from the left, to get the higher leaves. On the far left, a bright yellow dinosaur is about to join the meal.

How do you develop a scientific hypothesis?

In order to develop a hypothesis, one should have:

  • A good  testable question
  • Understanding of the dependent, independent and control  variables  of interest
  • Some prior knowledge, such as from observations and research
  • Thoughts about how the inquiry could be done (the method)

For example, students may begin with the question:

How does the duration of light exposure affect the surface area of tomato plant leaves?

The variables are:

  • Independent = duration of light
  • Dependent = surface area of plant leaves
  • Controlled = water, soil, seed source, etc.

How then do we formulate a hypothesis from this testable question? A good hypothesis tends to follow the format:

If  we do/change this 

Then  this will happen/be observed, because  we know this., if  these changes are made to a certain independent variable,, then  will we observe a change in a specific dependent variable, because  of our prior knowledge and research..

In the example above, the students have identified that they are interested in exploring how the duration of light affects plants, perhaps exposing plants from the same batch of seeds to light for different numbers of hours (e.g., one hour, two hours, etc.). Knowing that plants need light to grow (from prior knowledge or research), then they may hypothesize that the leaves of a plant may be larger given a longer exposure to light. Knowing all of this, their hypothesis might be:

If  we expose plants to a greater number of hours of light,  then  the surface area of the tomato plant leaves will be larger  because  light affects plant growth.

What makes for a good hypothesis.

A good hypothesis is:

  • A statement  The hypothesis is  not  the same as the testable question. The hypothesis is a tentative explanation of what is thought will happen during the inquiry.
  • Testable  What is changed (independent variable) and what is affected by the change (dependent variable) should be measurable and observable.
  • Falsifiable  A good hypothesis can be either supported or shown to be false by the data collected.
  • Clear.  It should be obvious what will be tested, how it will be tested (what will be measured to prove or disprove the hypothesis), and what is expected to happen.

A good question and hypothesis should also help students find answers that are not obvious to them or generally known. For example, most students will know that if you do not water a plant, it will die, so developing a hypothesis such as:

If  we stop watering our plants  then  the plants will die  because  plants need water in order to live.

is overly simplistic and will not help students expand their knowledge. A good experimental inquiry will help students discover things they do not already know.

Misconception Alert The goal of a hypothesis is NOT for a student to be “right.” Having evidence that shows a hypothesis to be false is just as important as having evidence that shows it to be true. A hypothesis is NOT something you prove – it is something you test!

How to develop a Tomatosphere™ hypothesis 

In the Seed Investigation, a testable question is provided to the students:

How does exposure to the space environment or space-like conditions affect the number of tomato seeds that germinate?

In the  variables  section, the dependent and independent variables were identified.

Independent variable :  Seed treatment – Some seeds have been to space or are exposed to space-like conditions in years when seeds do not go to space, while some seeds have not been to space or exposed to space-like conditions.

Dependent variable : Number of seeds that germinate.

What is not provided to the students is a hypothesis to follow from this question. Using the “if…..then…because….” format, have the students develop their hypotheses for the Tomatosphere™ testable question. For example:

If  tomato plant seeds are exposed to the conditions of space,  then  fewer ‘space’ seeds will germinate than non- ‘space’ seeds  because  radiation levels found in space may damage cells in the seeds.

This is not the only possible hypothesis, but it shows some understanding of how plants might be affected by space conditions (e.g., radiation affecting DNA in cells, microgravity affecting growth, etc.) which might be derived from prior knowledge or research.

Is this a good hypothesis? Yes

  • It is a statement.
  • It is testable.  What is changed (being in space or not) and what is affected by the change (number of seeds germinated) can be measured and observed.
  • It is falsifiable.  The student can use the data collected to be able to decide if it supports their hypothesis or if it shows the hypothesis is false (statement is false – more ‘space’ seeds germinate or the germination rate is the same).
  • It is clear.  It should be obvious what will be tested (seed germination), how it will be tested (seeds are grown to the point of germination), and what is expected to happen (fewer space seeds will germinate).

To assist with practicing writing a hypothesis, students could be provided with a checklist, such as this one, also available as a [ Google doc ] and [ PDF ].

Writing a Strong Hypothesis Checklist

Hypothesis is a statement that correctly follows the format:

"If _____ then ______ because _________

Hypothesis relates to the Testable Question

Hypothesis makes sense (based on observations and/or research)

Hypothesis can be falsified

Hypothesis includes a cause and effect relationship

Hypothesis could be tested with measurements

Hypothesis is easy to understand

Guided Practice

Have students read the following statements and determine if these are good, okay, or poor hypotheses and why.

Have students use the  Writing a Strong Hypothesis Checklist  for creating a Tomatosphere™ or other hypothesis.

Why is this a good hypothesis? ✓  It is a  statement  that follows the “if….then…because” format. ✓ It is testable.  What is changed (red light vs. green light) and what is affected by the change (size of leaves) is measurable and observable. ✓ It is falsifiable.  It can be supported by evidence (statement is true – leaves will be bigger, statement is untrue – leaves will be smaller or the same size). ✓ It is clear.  It is obvious what will be tested (two colours of light), how it will be tested (at six weeks of age the plant leaves will be measured), and what is expected to happen (plants grown in red light will have bigger leaves). B): 

Why is this a poor hypothesis? ✓  It is a  statement  that follows the “if….then…because” format. ✓ It is not testable.  The variables are very vague. What are the classroom conditions compared to the outdoor conditions? Is the interest in soil? Light? Temperature? What kinds of plants will be grown. ✗ It is not falsifiable.  It would be difficult to support or falsify with evidence because it is vague. ✗ It is not clear.  It is not obvious what will be tested (Soil? Temperature? Light?), how it will be tested and what is expected to happen (what does “better” mean? Taller? Bigger leaves? Flower sooner?). Have students work on changing this vague hypothesis into a more specific one by identifying variables to explore. C): 

Why is this just an “okay” hypothesis? ✓  It is a  statement  that follows the “if….then…because” format. ✗ It is somewhat testable.  What is changed (sugar water vs. regular water) is clear, but what is affected by the change (“better”) is vague. Will the plants be taller? Grow faster? ✗ It is not falsifiable.  It would be difficult to support or falsify with evidence because the “better” is vague. ✗ It is somewhat clear.   It is obvious what will be tested (maple syrup being added to the water) and how it will be tested, but what is expected to happen is not clear (what does “better” mean? Taller? Bigger leaves? Flower sooner?). Have students work on changing this somewhat vague hypothesis into a more specific one by identifying a dependent variable.

A Strong Hypothesis - Science Buddies  (2010) This blog post by Science Buddies explains the parts of a good hypothesis, and the role a hypothesis plays in the scientific process.

Theory vs. Hypothesis vs. Law… Explained!  (2015) This video (7:11 min.) from PBS Studios Be Smart explains how these words mean something totally different in science than in everyday speech, and how they all help us understand how the universe works.

Misconceptions about Science This page by Understanding Science at UC Berkeley gives a thorough definition of the word hypothesis, in a scientific context, as opposed to everyday language.

What is a Scientific Hypothesis?  (2022) This article by Alina Bradford at Live Science discusses what makes a hypothesis testable, the different types of hypotheses, and hypothesis vs. theory.

Writing a Hypothesis  (2013) This video (4:58 min.) by mreppsclassroom explains the purpose of a hypothesis and how to construct one.

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Hypothesis facts for kids

Cellarius Harmonia Macrocosmica - Hypothesis Ptolemaica

A hypothesis is a proposed explanation for some event or problem.

Cardinal Bellarmine gave a well known example of the older sense of the word in his warning to Galileo in the early 17th century: that he must not treat the motion of the Earth as a reality, but merely as a hypothesis.

Today, a hypothesis refers to an idea that needs to be tested . A hypothesis needs more work by the researcher in order to check it. A tested hypothesis that works, may become part of a theory or become a theory itself. The testing should be an attempt to prove the hypothesis is wrong. That is, there should be a way to falsify the hypothesis, at least in principle.

People often call a hypothesis an "educated guess".

Experimenters may test and reject several hypotheses before solving the problem.

A 'working hypothesis' is just a rough kind of hypothesis that is provisionally accepted as a basis for further research. The hope is that a theory will be produced, even if the hypothesis ultimately fails.

Hypotheses are especially important in science. Several philosophers have said that without hypotheses there could be no science. In recent years, philosophers of science have tried to integrate the various approaches to testing hypotheses, and the scientific method in general, to form a more complete system. The point is that hypotheses are suggested ideas which are then tested by experiments or observations .

In statistics , people talk about correlation : correlation is how closely related two events or phenomena are. A proposition (or hypothesis) that two events are related cannot be tested in the same way as a law of nature is tested. An example would be to see if some drug is effective to treat a given medical condition. Even if there is a strong correlation that indicates that this is the case, some samples would still not fit the hypothesis.

There are two hypotheses in statistical tests, called the null hypothesis and the alternative hypothesis. The null hypothesis states that there is no link between the phenomena. The alternative hypothesis states that there is some kind of link. The alternative hypothesis may take several forms. It can be two-sided (for example: there is some effect, in a yet unknown direction) or one-sided (the direction of the supposed relation, positive or negative, is fixed in advance).

Related pages

  • Falsifiability
  • Thought experiment
  • This page was last modified on 16 October 2023, at 16:53. Suggest an edit .

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Observation and Hypothesis

The Observation and Hypothesis lesson plan covers observations, inferences, and predictions and explains how all three are critical elements in the scientific method. By the end of this lesson, students will be able to write their own observation and hypothesis statements like a pro.

In this lesson plan, students will learn the differences between an observation, an inference, and a prediction or hypothesis. They will understand how observation and hypothesizing are critical elements in the scientific method. And finally, they will get to write their own observations and hypothesis statements.


Additional information, what our observation and hypothesis lesson plan includes.

Lesson Objectives and Overview: Observation and Hypothesis teaches students about two important steps of the scientific method. Students will discover the difference between an observation, a hypothesis, and an inference. They will also learn why these steps are so critical to the scientific method and how to develop their own observations and hypotheses. This lesson is for students in 3rd grade and 4th grade.

Classroom Procedure

Every lesson plan provides you with a classroom procedure page that outlines a step-by-step guide to follow. You do not have to follow the guide exactly. The guide helps you organize the lesson and details when to hand out worksheets. It also lists information in the yellow box that you might find useful. You will find the lesson objectives, state standards, and number of class sessions the lesson should take to complete in this area. In addition, it describes the supplies you will need and what and how you need to prepare beforehand. For the activity of this lesson, you will need string cheese, almond slivers, candle holders, and matches or lighters. The practice station requires some prep work, so review the classroom procedure page guidelines and information in the “Student Supplies” for more information.

Options for Lesson

In the “Options for Lesson” section of the classroom procedure page, you will see some suggestions for additional activities or ideas to add to the lesson if you want to. You could integrate observations and inferences into other lessons by continuing to demonstrate the collection of data. For example, you can use this lesson in conjunction with math lessons on graphing to enhance the idea of data collection. Another option is to have students choose their own objects to bring to class and incorporate them into the stations for the practice worksheet. If there is a class pet (or one that could be brought in), you can observe and make predictions about the animal as a class.

Teacher Notes

The paragraph on this page provides a little more information or guidance on what to expect from the lesson. It explains that students will have the opportunity to learn about both qualitative and quantitative data. You can use the blank lines to record any thoughts or ideas you have as you prepare.


Using our senses.

The Observation and Hypothesis lesson plan includes two pages of content. The first thing students learn is that an observation involves gathering information using the five senses. It is, basically, something we notice about the world around us. The five senses are touch, hearing, smell, taste, and sight.

On this page, the lesson outlines each sense, the organ that generates or allows the sense, and the parts involved. For sight, the organ is the eyes, and the parts involved include the cornea, pupil, iris, lens, retina, and optic nerve. The sense of smell happens with the nose, involving the nostrils, nasal cavity, and olfactory nerve.

The tongue allows for the sense of taste using taste buds and nerves. Our sense of touch happens with the largest organ of the human body—the skin. The nerve endings in our skin allow us to use this sense. And finally, the sense of hearing happens with the ears using the ear canal, ear drum, and three small bones.

Qualitative vs. Quantitative

Scientists constantly make observations, and there are two types: qualitative and quantitative. Qualitative data is the kind that describes what we observe. It is sensory in nature, and we can use adjectives to describe this data. To gather such information, we can ask questions about how something feels, what it smells like, what color it is, and so on.

On the other hand, quantitative data is the kind that measures what we observe. These observations use numbers to measure things numerically. Scientists often use a tool or instrument for these kinds of observations, like a thermometer, scale, or ruler. To find this kind of information, we can ask questions about how many of something there are, what the size of something is, what the temperature is, and so on.

Both types of observations are valuable in science. Scientists record or photograph their observations so that others can use the information or learn new information. In fact, once someone makes an observation, people can then use it to make inferences about something. An inference is an explanation for an observation. We base inferences on prior knowledge and past experiences.

For example, if we observe wet grass on our neighbor’s lawn, we can infer that it rained the night before, they turned on the sprinkler, or some other reason. Each inference can explain why the grass is wet. And we would make such inferences based on our prior knowledge of how grass can become soggy.

Inferences are not the same thing as predictions. Inferences use evidence and reasoning to form an idea and look at what happened in the past and is happening in the present. Predictions, however, are guesses about what will happen in the future. Scientists observe natural phenomena and infer based on those observations. They also make predictions about what could happen in the future.


The Observation and Hypothesis lesson plan includes three worksheets: an activity worksheet, a practice worksheet, and a homework assignment. Each one will help students solidify their grasp of the material they learned throughout the lesson. You can refer to the classroom procedure guidelines to know when to hand out each worksheet.


As the teacher, you will be the one demonstrating for the students while they fill out the activity worksheet. Your instructions are in the guidelines on the classroom procedure page. As you perform the simple experiment of the candle and flame, students will record what they observe in the chart on the activity page. There are two columns, one for qualitative observations and one for quantitative. At the bottom are yellow boxes where students can write their inferences about the candle.


For the practice worksheet, students will look at four different objects. Using the four tables on the page, they will write qualitative observations in one column and quantitative in the other. They should record at least three or four things they observe about each object.


The homework assignment requires students to look at a picture of a dog waiting near the front door of a house. After looking at the photo, students will write one observation, one inference, and one prediction related to the picture.

Worksheet Answer Keys

The last page of the lesson plan document is an answer key for the homework worksheet. The answers are in red to make it easy for your to compare them to students’ work. Given the nature of the assignment, the answers are sample responses of what students might write. If you choose to administer the lesson pages to your students via PDF, you will need to save a new file that omits this page. Otherwise, you can simply print out the applicable pages and keep this one as reference for yourself when grading assignments.

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Scientific Method For Kids With Examples

Kids have questions about the world around them every day, and there is so much to learn through experimentation with simple materials. You can begin using the scientific method with elementary kids. Below we’ll share with you how and when to introduce the scientific method, the steps of the scientific method, and some easy scientific method experiments. There are so many great ways to enjoy science projects with kids!

how to use the scientific method with kids

What Is The Scientific Method?

The scientific method is a process or method of research. A problem is identified, information about the problem is gathered, a hypothesis or question is formulated from the information, and the hypothesis is put to the test with an experiment to prove or disprove its validity.

Sounds heavy… What in the world does that mean?!? It means you don’t need to try and solve the world’s biggest science questions! The scientific method is all about studying and learning things right around you.

As children develop practices that involve creating, gathering data evaluating, analyzing, and communicating, they can apply these critical thinking skills to any situation.

Note: The use of the best Science and Engineering Practices is also relevant to the topic of using the scientific method. Read more here and see if it fits your science planning needs.

Can Young Kids Use the Scientific Method?

Kids are great scientists at any age, and can use the scientific method in context to what they are learning. It can be adapted for any age!

The scientific method is a valuable tool for introducing kids to a logical way to solve scientific problems. Scientists use the scientific method to study, learn, and come up with an answer!

The scientific method is a process that helps double-check that answers are correct and the correct results are obtained through careful planning. Sometimes the guesses and questions change as you run your experiments.

Kids can use the scientific method too on questions that are relevant to them!

Let’s break the scientific method for kids down into six parts, and you can quickly see how each can be incorporated into your next science experiment.

What Are The Steps In The Scientific Method?

  • Make initial observations.
  • Come up with a question of interest that is based on the observations.
  • Develop a hypothesis or prediction to go along with the question.
  • Experiment and test.
  • Gather and record results of tests and experiments and draw conclusions.
  • Share and discuss results.

Whoa… Wait A  Minute! That sounds like a lot for a young kid!

You are correct. Depending on your kid’s abilities, following all the scientific method steps precisely will not go well. Someone will get frustrated, bored, and turned off by just how cool science can be. We do not want that to happen!

Using The Scientific Method For Preschool and Kindergarten

Use the scientific method steps as a guideline in the back of your mind. You can cover most of the steps by talking with your kids about…

  • What do they think will happen?
  • What is happening ?
  • What happened compared to what they thought would happen ?

No writing is required! It’s also best to pick pretty straightforward ideas that aren’t overly involved or complicated to set up and test. Kids always have burning questions and “what ifs.”

See if you can tackle their next “what if” using the scientific method by listening carefully to their conversations. You can even have them keep a journal with their “what if” questions for your next science time.

Learn more about Science Activities For Preschoolers and Kindergarten Science Experiments .

Now on to how to apply the scientific method for elementary kiddos and beyond.

Scientific Method Steps In Action

Learn more about the steps of the scientific method below, which are great for science at home with your kids or in the classroom! We have also included some simple scientific method experiments for you to enjoy.

Ice Science Experiments are perfect for this! Try these 3 today !

hypothesis definition science 4th grade

STEP 1: Make Observations

Tons of everyday activities would make for cool science experiments using the scientific method. Listen to what your kids talk about and see happening. My son noticed that ice melted pretty fast in his water.

Observation is simply noticing what’s happening through our senses or with tools like a magnifying glass. Observation is used to collect and record data, enabling scientists to construct and test hypotheses and theories.

Learn more about observations in science.

STEP 2: Come Up With A Question 

Your kids’ observations should lead to some sort of question. For my son and his ice observations, he came up with questions. Does ice melt faster in different liquids? His curiosity about what happens to the ice in liquids is a simple science experiment perfect for using the scientific method.

Next! Do some research and come up with ideas!

STEP 3: Develop A Prediction or Hypothesis

You have made your observations, you have your question, and now you need to make a prediction about what you think will happen.

A prediction is a guess at what might happen in an experiment based on observation or other information.

A hypothesis is not simply a guess! It’s a statement of what you believe will happen based on the information you have gathered.

My son hypothesizes that ice will melt faster in juice than in water.

STEP 4: Conduct An Experiment

We made a prediction that ice will melt faster in juice than it will in water, and now we have to test our hypothesis. We set up an experiment with a glass of juice, a glass of water, and an ice cube for each.

For the best experiments, only one thing should change! All the things that can be changed in a science experiment are called variables. There are three types of variables; independent, dependent, and controlled.

The independent variable is the one that is changed in the experiment and will affect the dependent variable. Here we will use different types of liquids to melt our ice cube in.

The dependent variable is the factor that is observed or measured in the experiment. This will be the melting of the ice cubes. Set up a stopwatch or set a time limit to observe the changes!

The controlled variable stays constant in the experiment. The liquids should be roughly the same temperature (as close as possible) for our ice melting experiment and measured to the same amount. So we left them out to come to room temperature. They could also be tested right out of the fridge!

You can find simple science experiments here with dependent and controlled variables.

STEP 5: Record Results and Draw Conclusions

Make sure to record what is happening as well as the results—note changes at specific time intervals or after one set time interval.

For example…

  • Record when each ice cube is completely melted.
  • Add drawings if you wish of the setup up and the end results.
  • Was your prediction accurate? If it was inaccurate, record why.
  • Write out a final conclusion to your experiment.

STEP 6: Communicate Your Results

This is the opportunity to talk about your hypothesis, experiment, results, and conclusion!

ALTERNATIVE IDEAS: Switch out an ice cube for a lollipop or change the liquids using vinegar and cooking oil.

Now you have gone through the steps of the scientific method, read on for more fun scientific method experiments to try!

Free printable scientific method worksheets!

hypothesis definition science 4th grade

Fun Scientific Method Experiments

Sink or float experiment.

A Sink or Float experiment is great for practicing the steps of the scientific method with younger kids.

Grab this FREE printable sink or float experiment

hypothesis definition science 4th grade

Here are a few of our favorite scientific method experiments, which are great for elementary-age kids . Of course, you can find tons more awesome and doable science projects for kids here!

Magic Milk Experiment

Start with demonstrating this delightful magic milk experiment. Then get kids to apply the steps of the scientific method by coming up with a question to investigate. What happens when you change the type of milk used?

hypothesis definition science 4th grade

What Dissolves In Water

Investigate  what solids dissolve in water  and what do not. Here’s a super fun science experiment for kids that’s very easy to set up! Learn about solutions, solutes, and solvents through experimenting with water and common kitchen ingredients.

Apple Browning Experiment

Investigate how to keep apples from turning brown with this apple oxidation experiment . What can you add to cut apples to stop or slow the oxidation process?

hypothesis definition science 4th grade

Freezing Water Experiment

Will it freeze? What happens to the freezing point of water when you add salt?

Viscosity Experiment

Learn about the viscosity of fluids with a simple  viscosity experiment . Grab some marbles and add them to different household liquids to find out which one will fall to the bottom first. 

Seed Germination Experiment

Set up a simple seed germination experiment .

hypothesis definition science 4th grade

Catapult Experiment

Make a simple popsicle stick catapult and use one of our experiment ideas to investigate from rubber band tension to changes in launch angle and more. How far can you fling your objects? Take measurements and find out.

DIY popsicle stick catapult Inexpensive STEM activity

Floating Orange

Investigate whether an orange floats or sinks in water, and what happens if you use different types of oranges. Learn about buoyancy and density with a simple ingredient from the kitchen, an orange.

hypothesis definition science 4th grade

Bread Mold Experiment

Grow mold on bread for science, and investigate how factors such as moisture, temperature, and air affect mold growth. 

Eggshell Strength Experiment

Test how strong an egg is with this eggshell strength experiment . Grab some eggs, and find out how much weight an egg can support.

hypothesis definition science 4th grade

Free Printable Science Fair Starter Guide

Are you looking to plan a science fair project, make a science fair board, or want an easy guide to set up science experiments?

Learn more about prepping for a science fair and grab this free printable science fair project pack here!

If you want a variety of science fair experiments with instructions, make sure to pick up a copy of our Science Project Pack in the shop.

hypothesis definition science 4th grade

Bonus STEM Projects For Kids

STEM activities include science, technology, engineering, and mathematics. As well as our kids science experiments, we have lots of fun STEM activities for you to try. Check out these STEM ideas below…

  • Building Activities
  • Engineering Projects For Kids
  • What Is Engineering For Kids?
  • Coding Activities For Kids
  • STEM Worksheets
  • Top 10 STEM Challenges For Kids

Printable Science Projects Pack

If you’re looking to grab all of our printable science projects in one convenient place plus exclusive worksheets and bonuses like a STEAM Project pack, our Science Project Pack is what you need! Over 300+ Pages!

  • 90+ classic science activities  with journal pages, supply lists, set up and process, and science information.  NEW! Activity-specific observation pages!
  • Best science practices posters  and our original science method process folders for extra alternatives!
  • Be a Collector activities pack  introduces kids to the world of making collections through the eyes of a scientist. What will they collect first?
  • Know the Words Science vocabulary pack  includes flashcards, crosswords, and word searches that illuminate keywords in the experiments!
  • My science journal writing prompts  explore what it means to be a scientist!!
  • Bonus STEAM Project Pack:  Art meets science with doable projects!
  • Bonus Quick Grab Packs for Biology, Earth Science, Chemistry, and Physics

hypothesis definition science 4th grade


A great post and sure to help extend children’s thinking! I would like to download the 6 steps but the blue download button doesn’t seem to be working for me.

Thank you! All fixed. You should be able to download now!

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it is so great, thanks a lot.

This helped for a science project.Thanks so much.

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Hypothesis For Kids

hypothesis definition science 4th grade

Crafting a hypothesis isn’t just for scientists in white lab coats; even young budding researchers can join in the fun! When kids learn to frame their curious wonders as hypothesis statements, they pave the way for exciting discoveries. Our guide breaks down the world of hypothesis writing into kid-friendly chunks, complete with relatable thesis statement examples and easy-to-follow tips. Dive in to spark a love for inquiry and nurture young scientific minds!

What is an example of a Hypothesis for Kids?

Question: Do plants grow taller when they are watered with coffee instead of water?

Hypothesis: If I water a plant with coffee instead of water, then the plant will not grow as tall because coffee might have substances that aren’t good for plants.

This hypothesis is based on a simple observation or question a child might have, and it predicts a specific outcome (the plant not growing as tall) due to a specific condition (being watered with coffee). It’s presented in simple language suitable for kids.

100 Kids Hypothesis Statement Examples

Kids Hypothesis Statement Examples

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Children’s innate curiosity lays the foundation for numerous questions about the world around them. Framing these questions as good hypothesis statements can transform them into exciting learning experiments. Presented below are relatable and straightforward examples crafted especially for young minds, offering them a structured way to articulate their wonders and predictions.

  • Sunlight & Plant Growth : If a plant gets more sunlight, then it will grow taller.
  • Sugary Drinks & Tooth Decay : Drinking sugary drinks daily will lead to faster tooth decay.
  • Chocolates & Energy : Eating chocolate will make me feel more energetic.
  • Moon Phases & Sleep : I’ll sleep more during a full moon night.
  • Homework & Weekend Moods : If I finish my homework on Friday, I’ll be happier over the weekend.
  • Pets & Happiness : Owning a pet will make a child happier.
  • Rain & Worms : Worms come out more after it rains.
  • Shadows & Time of Day : Shadows are longer in the evening than at noon.
  • Snow & School Holidays : More snow means there’s a better chance of school being canceled.
  • Ice Cream & Brain Freeze : Eating ice cream too fast will give me a brain freeze.
  • Video Games & Dreams : Playing video games before bed might make my dreams more vivid.
  • Green Vegetables & Strength : Eating more green vegetables will make me stronger.
  • Bicycles & Balance : The more I practice, the better I’ll get at riding my bike without training wheels.
  • Stars & Wishes : If I wish on the first star I see at night, my wish might come true.
  • Cartoons & Laughing : Watching my favorite cartoon will always make me laugh.
  • Soda & Bone Health : Drinking soda every day will make my bones weaker.
  • Beach Visits & Sunburn : If I don’t wear sunscreen at the beach, I’ll get sunburned.
  • Loud Noises & Pet Behavior : My cat hides when she hears loud noises.
  • Bedtime & Morning Energy : Going to bed early will make me feel more energetic in the morning.
  • Healthy Snacks & Hunger : Eating a healthy snack will keep me full for longer. …
  • Toys & Sharing : The more toys I have, the more I want to share with my friends.
  • Homemade Cookies & Taste : Homemade cookies always taste better than store-bought ones.
  • Books & Imagination : The more books I read, the more adventures I can imagine.
  • Jumping & Height : The more I practice, the higher I can jump.
  • Singing & Mood : Singing my favorite song always makes me happy.
  • Snowmen & Temperature : If the temperature rises, my snowman will melt faster.
  • Costumes & Play : Wearing a costume will make playtime more fun.
  • Gardening & Patience : Waiting for my plants to grow teaches me patience.
  • Night Lights & Sleep : Having a night light makes it easier for me to sleep.
  • Handwriting & Practice : The more I practice, the better my handwriting will become.
  • Painting & Creativity : Using more colors in my painting lets me express my creativity better.
  • Puzzles & Problem Solving : The more puzzles I solve, the better I become at problem-solving.
  • Dancing & Coordination : The more I dance, the more coordinated I will become.
  • Stargazing & Constellations : If I stargaze every night, I’ll recognize more constellations.
  • Bird Watching & Species Knowledge : The more I watch birds, the more species I can identify.
  • Cooking & Skill : If I help in the kitchen often, I’ll become a better cook.
  • Swimming & Confidence : The more I swim, the more confident I become in the water.
  • Trees & Birds’ Nests : The taller the tree, the more likely it is to have birds’ nests.
  • Roller Skating & Balance : If I roller skate every weekend, I’ll improve my balance.
  • Drawing & Observation : The more I draw, the better I become at observing details.
  • Sandcastles & Water : If I use wet sand, I can build a stronger sandcastle.
  • Hiking & Endurance : The more I hike, the farther I can walk without getting tired.
  • Camping & Outdoor Skills : If I go camping often, I’ll learn more about surviving outdoors.
  • Magic Tricks & Practice : The more I practice a magic trick, the better I’ll get at performing it.
  • Stickers & Collection : If I collect stickers, my album will become more colorful.
  • Board Games & Strategy : The more board games I play, the better strategist I’ll become.
  • Pets & Responsibility : The more I take care of my pet, the more responsible I become.
  • Music & Concentration : Listening to calm music while studying will help me concentrate better.
  • Photographs & Memories : The more photos I take, the more memories I can preserve.
  • Rainbows & Rain : If it rains while the sun is out, I might see a rainbow.
  • Museums & Knowledge : Every time I visit a museum, I learn something new.
  • Fruits & Health : Eating more fruits will keep me healthier.
  • Stories & Vocabulary : The more stories I listen to, the more new words I learn.
  • Trees & Fresh Air : The more trees there are in a park, the fresher the air will be.
  • Diary & Feelings : Writing in my diary helps me understand my feelings better.
  • Planets & Telescopes : If I look through a telescope, I’ll see more planets clearly.
  • Crafting & Creativity : The more crafts I make, the more creative I become.
  • Snowflakes & Patterns : Every snowflake has a unique pattern.
  • Jokes & Laughter : The funnier the joke, the louder I’ll laugh.
  • Riddles & Thinking : Solving riddles makes me think harder.
  • Nature Walks & Observations : The quieter I am on a nature walk, the more animals I’ll spot.
  • Building Blocks & Structures : The more blocks I use, the taller my tower will be.
  • Kites & Wind : If there’s more wind, my kite will fly higher.
  • Popcorn & Movie Nights : Watching a movie with popcorn makes it more enjoyable.
  • Stars & Wishes : If I see a shooting star, I should make a wish.
  • Diets & Energy : Eating a balanced diet gives me more energy for playtime.
  • Clay & Sculptures : The more I play with clay, the better my sculptures will be.
  • Insects & Magnifying Glass : Using a magnifying glass will let me see more details of tiny insects.
  • Aquarium Visits & Marine Knowledge : Every time I visit the aquarium, I discover a new marine creature.
  • Yoga & Flexibility : If I practice yoga daily, I’ll become more flexible.
  • Toothpaste & Bubbles : The more toothpaste I use, the more bubbles I’ll get while brushing.
  • Journals & Memories : Writing in my journal every day helps me remember special moments.
  • Piggy Banks & Savings : The more coins I save, the heavier my piggy bank will get.
  • Baking & Measurements : If I measure ingredients accurately, my cake will turn out better.
  • Coloring Books & Art Skills : The more I color, the better I get at staying inside the lines.
  • Picnics & Outdoor Fun : Having a picnic makes a sunny day even more enjoyable.
  • Recycling & Environment : The more I recycle, the cleaner my environment will be.
  • Treasure Hunts & Discoveries : Every treasure hunt has a new discovery waiting.
  • Milk & Bone Health : Drinking milk daily will make my bones stronger.
  • Puppet Shows & Stories : The more puppet shows I watch, the more stories I learn.
  • Field Trips & Learning : Every field trip to a new place teaches me something different.
  • Chores & Responsibility : The more chores I do, the more responsible I feel.
  • Fishing & Patience : Fishing teaches me to be patient while waiting for a catch.
  • Fairy Tales & Imagination : Listening to fairy tales expands my imagination.
  • Homemade Pizza & Toppings : The more toppings I add, the tastier my homemade pizza will be.
  • Gardens & Butterflies : If I plant more flowers, I’ll see more butterflies in my garden.
  • Raincoats & Puddles : Wearing a raincoat lets me jump in puddles without getting wet.
  • Gymnastics & Balance : The more I practice gymnastics, the better my balance will be.
  • Origami & Craft Skills : The more origami I fold, the better my craft skills become.
  • Basketball & Shooting Skills : The more I practice, the better I get at shooting baskets.
  • Fireflies & Night Beauty : Catching fireflies makes summer nights magical.
  • Books & Knowledge : The more books I read, the smarter I become.
  • Pillows & Forts : With more pillows, I can build a bigger fort.
  • Lemonade & Summers : Drinking lemonade makes hot summer days refreshing.
  • Bicycles & Balance : The more I practice, the better I get at riding my bike without training wheels.
  • Pencils & Drawings : If I have colored pencils, my drawings will be more colorful.
  • Ice Cream & Happiness : Eating ice cream always makes me happy.
  • Beach Visits & Shell Collections : Every time I visit the beach, I find new shells for my collection.
  • Jump Ropes & Fitness : The more I jump rope, the fitter I become.
  • Tea Parties & Imagination : Hosting tea parties lets my imagination run wild.

Simple Hypothesis Statement Examples for Kids

Simple hypothesis are straightforward predictions that can be tested easily. They help children understand the relationship between two variables. Here are some examples tailored just for kids.

  • Plants & Sunlight : Plants placed near the window will grow taller than those in the dark.
  • Chocolates & Happiness : Eating chocolates can make kids feel happier.
  • Rain & Puddles : The more it rains, the bigger the puddles become.
  • Homework & Learning : Doing homework helps kids understand lessons better.
  • Toys & Sharing : Sharing toys with friends makes playtime more fun.
  • Pets & Care : Taking care of a pet fish helps it live longer.
  • Storytime & Sleep : Listening to a bedtime story helps kids sleep faster.
  • Brushing & Cavity : Brushing teeth daily prevents cavities.
  • Games & Skill : Playing a new game every day improves problem-solving skills.
  • Baking & Patience : Waiting for cookies to bake teaches patience.

Hypothesis Statement Examples for Kids Psychology

Child psychology hypothesis delves into how kids think, behave, and process emotions. These hypotheses help understand the psychological aspects of children’s behaviors.

  • Emotions & Colors : Kids might feel calm when surrounded by blue and energetic with red.
  • Friendship & Self-esteem : Making friends can boost a child’s self-confidence.
  • Learning Styles & Memory : Some kids remember better by seeing, while others by doing.
  • Play & Development : Pretend play is crucial for cognitive development.
  • Rewards & Motivation : Giving small rewards can motivate kids to finish tasks.
  • Music & Mood : Listening to soft music can calm a child’s anxiety.
  • Sibling Bonds & Sharing : Having siblings can influence a child’s willingness to share.
  • Feedback & Performance : Positive feedback can improve a kid’s academic performance.
  • Outdoor Play & Attention Span : Playing outside can help kids concentrate better in class.
  • Dreams & Reality : Kids sometimes can’t differentiate between dreams and reality.

Hypothesis Examples in Kid Friendly Words

Phrasing hypothesis in simple words makes it relatable and easier for kids to grasp. Here are examples with kid-friendly language.

  • Socks & Warmth : Wearing socks will keep my toes toasty.
  • Jumping & Energy : The more I jump, the more energy I feel.
  • Sandcastles & Water : A little water makes my sandcastle stand tall.
  • Stickers & Smiles : Getting a sticker makes my day shine brighter.
  • Rainbows & Rain : After the rain, I might see a rainbow.
  • Slides & Speed : The taller the slide, the faster I go.
  • Hugs & Love : Giving hugs makes me and my friends feel loved.
  • Stars & Counting : The darker it is, the more stars I can count.
  • Paint & Mess : The more paint I use, the messier it gets.
  • Bubbles & Wind : If I blow my bubble wand, the wind will carry them high.

Hypothesis Statement Examples for Kids in Research

Even in a research setting, research hypothesis should be age-appropriate for kids. These examples focus on concepts children might encounter in structured studies.

  • Reading & Vocabulary : Kids who read daily might have a richer vocabulary.
  • Games & Math Skills : Playing number games can improve math skills.
  • Experiments & Curiosity : Conducting science experiments can make kids more curious.
  • Doodles & Creativity : Drawing daily might enhance a child’s creativity.
  • Learning Methods & Retention : Kids who learn with visuals might remember lessons better.
  • Discussions & Understanding : Talking about a topic can deepen understanding.
  • Observation & Knowledge : Observing nature can increase a kid’s knowledge about the environment.
  • Puzzles & Cognitive Skills : Solving puzzles regularly might enhance logical thinking.
  • Music & Rhythmic Abilities : Kids who practice music might develop better rhythm skills.
  • Teamwork & Social Skills : Group projects can boost a child’s social skills.

Hypothesis Statement Examples for Kids Science Fair

Science fairs are a chance for kids to delve into the world of experiments and observations. Here are hypotheses suitable for these events.

  • Magnet & Metals : Certain metals will be attracted to a magnet.
  • Plants & Colored Light : Plants might grow differently under blue and red lights.
  • Eggs & Vinegar : An egg in vinegar might become bouncy.
  • Solar Panels & Sunlight : Solar panels will generate more power on sunny days.
  • Volcanoes & Eruptions : Mixing baking soda and vinegar will make a mini eruption.
  • Mirrors & Reflection : Shiny surfaces can reflect light better than dull ones.
  • Battery & Energy : Fresh batteries will make a toy run faster.
  • Density & Floating : Objects with lower density will float in water.
  • Shadows & Light Source : Moving the light source will change the shadow’s direction.
  • Freezing & States : Water turns solid when kept in the freezer.

Hypothesis Statement Examples for Science Experiments

Experiments let kids test out their predictions in real-time. Here are hypotheses crafted for various scientific tests.

  • Salt & Boiling Point : Adding salt will make water boil at a higher temperature.
  • Plants & Music : Playing music might affect a plant’s growth rate.
  • Rust & Moisture : Metals kept in a moist environment will rust faster.
  • Candles & Oxygen : A candle will burn out faster in an enclosed jar.
  • Fruits & Browning : Lemon juice can prevent cut fruits from browning.
  • Yeast & Sugar : Adding sugar will make yeast activate more vigorously.
  • Density & Layers : Different liquids will form layers based on their density.
  • Acids & Bases : Red cabbage juice will change color in acids and bases.
  • Soil Types & Water : Sandy soil will drain water faster than clay.
  • Thermometers & Temperatures : Thermometers will show higher readings in the sun.

Hypothesis Statement Examples for Kids At Home

These hypotheses are crafted for experiments and observations kids can easily make at home, using everyday items.

  • Chores & Time : Setting a timer will make me finish my chores faster.
  • Pets & Behavior : My cat sleeps more during the day than at night.
  • Recycling & Environment : Recycling more can reduce the trash in my home.
  • Cooking & Tastes : Adding spices will change the taste of my food.
  • Family Time & Bonding : Playing board games strengthens our family bond.
  • Cleaning & Organization : Organizing my toys daily will keep my room tidier.
  • Watering & Plant Health : Watering my plant regularly will keep its leaves green.
  • Decor & Mood : Changing the room decor can influence my mood.
  • Journals & Memories : Writing in my journal daily will help me remember fun events.
  • Photos & Growth : Taking monthly photos will show how much I’ve grown.

How do you write a hypothesis for kids? – A Step by Step Guide

Step 1: Start with Curiosity Begin with a question that your child is curious about. This could be something simple, like “Why is the sky blue?” or “Do plants need sunlight to grow?”

Step 2: Observe and Research Before formulating the hypothesis, encourage your child to observe the world around them. If possible, read or watch videos about the topic to gather information. The idea is to get a general understanding of the subject.

Step 3: Keep it Simple For kids, it’s essential to keep the hypothesis straightforward and concise. Use language that is easy to understand and relatable to their age.

Step 4: Make a Predictable Statement Help your child frame their hypothesis as an “If… then…” statement. For example, “If I water a plant every day, then it will grow taller.”

Step 5: Ensure Testability Ensure that the hypothesis can be tested using simple experiments or observations. It should be something they can prove or disprove through hands-on activities.

Step 6: Avoid Certainty Teach kids that a hypothesis is not a definitive statement of fact but rather a best guess based on what they know. It’s okay if the hypothesis turns out to be wrong; the learning process is more important.

Step 7: Review and Refine After forming the initial hypothesis, review it with your child. Discuss if it can be made simpler or clearer. Refinement aids in better understanding and testing.

Step 8: Test the Hypothesis This is the fun part! Plan an experiment or set of observations to test the hypothesis. Whether the hypothesis is proven correct or not, the experience provides a learning opportunity.

Tips for Writing Hypothesis for Kids

  • Encourage Curiosity : Always encourage your child to ask questions about the world around them. It’s the first step to formulating a hypothesis.
  • Use Familiar Language : Use words that the child understands and can relate to. Avoid jargon or technical terms.
  • Make it Fun : Turn the process of forming a hypothesis into a game or a storytelling session. This will keep kids engaged.
  • Use Visual Aids : Kids often respond well to visuals. Drawing or using props can help in understanding and formulating the hypothesis.
  • Stay Open-minded : It’s essential to teach kids that it’s okay if their hypothesis is wrong. The process of discovery and learning is what’s crucial.
  • Practice Regularly : The more often kids practice forming hypotheses, the better they get at it. Use everyday situations as opportunities.
  • Link to Real-life Scenarios : Relate the hypothesis to real-life situations or personal experiences. For instance, if discussing plants, you can relate it to a plant you have at home.
  • Collaborate : Sometimes, two heads are better than one. Encourage group activities where kids can discuss and come up with hypotheses together.
  • Encourage Documentation : Keeping a journal or notebook where they document their hypotheses and results can be a great learning tool.
  • Celebrate Efforts : Regardless of whether the hypothesis was correct, celebrate the effort and the learning journey. This reinforces the idea that the process is more important than the outcome.


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Hypothesis Examples

A hypothesis has classical been referred to as an educated guess. In the context of the scientific method, this description is somewhat correct. After a problem is identified, the scientist would typically conduct some research about the problem and then make a hypothesis about what will happen during his or her experiment. A better explanation of the purpose of a hypothesis is that a hypothesis is a proposed solution to a problem. Hypotheses have not yet been supported by any measurable data. In fact, we often confuse this term with the word theory in our everyday language. People say that they have theories about different situations and problems that occur in their lives but a theory implies that there has been much data to support the explanation. When we use this term we are actually referring to a hypothesis. For example, someone might say, "I have a theory about why Jane won't go out on a date with Billy." Since there is no data to support this explanation, this is actually a hypothesis. In the world of statistics and science, most hypotheses are written as "if...then" statements. For example someone performing experiments on plant growth might report this hypothesis: "If I give a plant an unlimited amount of sunlight, then the plant will grow to its largest possible size." Hypotheses cannot be proven correct from the data obtained in the experiment, instead hypotheses are either supported by the data collected or refuted by the data collected.

1. If I replace the battery in my car, then my car will get better gas mileage.

2. If I eat more vegetables, then I will lose weight faster.

3. If I add fertilizer to my garden, then my plants will grow faster.

4. If I brush my teeth every day, then I will not develop cavities.

5. If I take my vitamins every day, then I will not feel tired.

6. If 50 mL of water are added to my plants each day and they grow, then adding 100 mL of water each day will make them grow even more.

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Mario J. Molina: Environmental Hero

  • As a child in the 1950s, Mario J. Molina looked at a drop of pond water under a microscope. Within this realm of tiny organisms, he discovered his deep passion for science.
  • Young Molina dove headfirst into learning. He acquired several chemistry sets. He also turned an unused bathroom of his Mexico City home into a lab. When he was 11, Molina left home to attend a boarding school in Europe. He wanted to speak German because many chemists did.
  • In school, Molina worked hard and learned all that he could. Eventually, he became a college professor.
  • As a professor, Molina tackled a question that no other scientist had before. It was: How do chlorofluorocarbons (CFCs) affect the atmosphere? CFCs are chemicals once used to cool refrigerators. They were also used in things like hair spray. At this time in the 1970s, the public believed that CFCs were safe to use.
  • However, Molina discovered something else. After release, CFCs rise up into Earth’s atmosphere. There, solar radiation breaks them down into something called chlorine. Chlorine destroys the ozone layer, which shields Earth from the sun’s harmful rays.
  • Molina, along with other scientists, noticed that the ozone layer was damaged and realized CFCs were to blame. In 1985, a British team of scientists found an ozone hole. It was above Antarctica. Many believed that it caused increased rates of skin cancer in the Southern Hemisphere. Molina’s group continued to study the ozone hole.
  • World leaders at the time became very worried. They pledged to end emissions of CFCs. Industries stopped making them. Damage to the ozone hole ceased. It’s expected to fully repair in the twenty-first century.
  • Molina has since received the Nobel Prize and other awards. An asteroid was named after him. Today, Molina continues to research important scientific issues.
  • That one drop of water brought a whole new view for Molina and for our Earth.
  • (Choice A)   The Worldwide Ban on CFCs A The Worldwide Ban on CFCs
  • (Choice B)   One Man’s Quest to Save the Ozone Layer B One Man’s Quest to Save the Ozone Layer
  • (Choice C)   Danger in the Southern Hemisphere C Danger in the Southern Hemisphere
  • (Choice D)   The Importance of Wearing Sunscreen D The Importance of Wearing Sunscreen

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50 Exciting 4th Grade Science Projects and Experiments

Did you know you can make plastic from milk?

Collage of 4th grade science projects, including marble energy transfer and model seismometer

Nothing gets kids more excited for science than hands-on experiments! Watch your 4th grade science students’ eyes light up when they try some of these activities. You’ll find physics, biology, engineering, chemistry, and more. These projects are easy to set up and really help drive the learning home. Get ready for some science fun!

To help you find the right 4th grade science projects and activities, we’ve rated them all based on difficulty and materials:


  • Easy: Low or no-prep experiments you can do pretty much any time
  • 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

4th Grade Science Fair Projects

4th grade stem challenge science projects, 4th grade motion and energy science activities.

  • More 4th Grade Science Projects and Experiments

These 4th grade experiments also work well as science fair projects. Try changing up the variables to turn it into a real experiment, then form a hypothesis and find out what happens.

Blow unpoppable bubbles

Student's gloved hand holding a soap bubble next to a window (Fourth Grade Science)

Difficulty: Easy / Materials: Medium

A soap bubble you can hold in your hand? It’s true! A little glycerin makes the soap bubble layers stronger, so you can even toss them gently from person to person.

Learn more: Unpoppable Bubbles Experiment at Learning Resources

Grow crystal names

Crystalized pipe cleaner letters against a black background

No list of 4th grade science projects would be complete without crystals! Kids of all ages love growing crystals, making this an ideal way to learn about supersaturated solutions. The classic experiment gets a new twist when you have kids shape pipe cleaners into their own names first.

Learn more: Crystal Letters at Playdough to Plato

Grow bacteria in petri dishes

6 petri dishes growing a variety of molds and bacteria

Difficulty: Medium / Materials: Medium

Your students will truly feel like scientists when they perform this classic experiment. They’ll prep the dishes with agar, swab different surfaces, and see what bacteria they grow. It’s gross science, but it’s also easy and impressive.

Learn more: Growing Bacteria at Steve Spangler Science

See coastal erosion in action

Plastic bin filled with sand, shells, and water to simulate a beach, with a hand holding a plastic bottle in the water (Fourth Grade Science)

Here’s a cool experiment to include in your unit on oceans. Build a miniature coastline, then see how wave action erodes the shore.

Learn more: Erosion Experiment at Little Bins for Little Hands

Erupt a lemon volcano

Cut lemon in a blue bowl covered in colorful fizzy foam

Difficulty: Easy / Materials: Basic

Early chemistry experiments with acids and bases are always a lot of fun. This one uses the natural acids of lemon juice and adds a little food coloring to up the wow factor.

Learn more: Lemon Volcano at STEAM Powered Family

Sink and float to explore density

Series of glasses filled with liquid labeled baking soda water, sugar water, control plain water, and salt water, with red and blue objects floating in each

Adding items like salt or sugar to water changes its density, as does the temperature itself. Turn this into a 4th grade science fair project by experimenting with different solutions and forming hypotheses about the results.

Learn more: Salt Water Density at Science Kiddo

Discover a density rainbow

Difficulty: Medium / Materials: Basic

Colorful, simple, and impressive: It’s the trifecta of 4th grade science experiments! Wow your students by layering colored sugar water as you learn about density, adhesion, and cohesion.

Transform milk into plastic

Plastic seems incredibly modern, but people have been making casein plastic from milk for centuries. In this 4th grade science project, students experiment to create the formula for the best milk plastic. They’ll be amazed at the results!

Simulate an earthquake

Fourth grade science teacher's hand shaking a pan of Jello topped with a house model made of toothpicks and marshmallows

The ground under our feet may feel solid, but an earthquake changes that pretty quickly. Use Jell-O to simulate the Earth’s crust, then see if you can build an earthquake-proof structure for a practical and fascinating 4th grade science fair project.

Learn more: Earthquake Simulation at Teaching Science

Test Sharpie solubility

Coffee filters colored with marker, dipped into vinegar, rubbing alcohol, and water

Find out if Sharpie markers are really permanent with this 4th grade science project that uses the scientific method to explore solutes and solvents.

Learn more: Sharpie Solubility at Around the Kampfire

Find out if mood rings really work

Student's hand holding a blue mood ring in front of a thermometer

Apply the rigors of the scientific method to mood rings ! Find out what makes mood rings change color, then see if they really reflect a person’s mood.

Learn more: Mood Rings Validity Test at Education.com

Create a new plant or animal

Science project showing an imaginary plant called a Snap-a-Doodle

Kids will really get into this project, indulging their creativity as they invent a plant or animal that’s never been seen before. They’ll need to be able to explain the biology behind it all, though, making this an in-depth project you can tailor to any class.

Learn more: Create an Organism at I Love 2 Teach

Investigate decomposition

Plastic bag containing a plate of rotting food

Difficulty: Easy / Materials: Easy

Yup, it’s gross … so kids will love it! Seal food items in a plastic bag and experiment to see what factors affect their decomposition, helped along by a heaping dose of mold.

Learn more: Decomposition at Mystery Science

Assemble a lung model

With just a few supplies including balloons and a plastic bottle, you can make an impressive working model of human lungs. This makes a very cool 4th grade science fair project.

Explore the causes of tooth decay

They hear it from their parents all the time, but this experiment will prove to your students once and for all what can happen to their teeth when exposed to different drinks such as soda and milk. This is one of those classic 4th grade science fair projects every kid should try.

For students who love to tinker, STEM challenges can spark incredible 4th grade science fair projects. Here are some of our favorites for this age group.

Engineer a drinking-straw roller coaster

Student building a roller coaster of drinking straws for a ping pong ball (Fourth Grade Science)

STEM challenges are always a hit with kids. We love this one, which only requires basic supplies like drinking straws . ( Get more 4th grade STEM challenges here. )

Learn more: Drinking Straw Roller Coaster at Frugal Fun for Boys and Girls

Make a wigglebot

Wigglebot made of a plastic cup and markers

Who knew electricity could be so adorable? Explore the science behind batteries and motors by creating a simple “wigglebot.” Experiment with weights to throw the motor off balance and create fun designs.

Learn more: Wigglebot at Research Parent

Construct a working flashlight

Student using a flashlight made from a few supplies and an index card

You’ll only need a few supplies to guide your students in building their own LED flashlights. They’ll learn how electricity travels and the way circuits work. The slideshow available through the link makes this lesson a breeze for teachers too.

Learn more: DIY Flashlight at Mystery Science

Build a hovercraft

Inflated yellow balloon attached to a CD by a bottle cap

It’s not exactly the same model the military uses, but this simple hovercraft is a lot easier to build. An old CD and a balloon help demonstrate air pressure and friction in this fun 4th grade science experiment.

Learn more: DIY Hovercraft at Education.com

Create a smartphone projector

Cardboard box with a magnifying glass embedded in it, with a smart phone

No projector in your classroom yet? No problem! Have your students help you construct one for your smartphone using a cardboard box and large magnifying glass . They’ll learn about convex lenses and how the brain processes images too.

Learn more: DIY Smartphone Projector at The STEM Laboratory

Set up a pulley system

Pulley system made of cans and yarn mounted on a piece of cardboard

The science of machines never fails to fascinate kids. In this experiment, they’ll design their own pulley system to make it easier to lift an object.

Learn more: DIY Pulley at 123 Homeschool 4 Me

Design a working elevator

Engineering activities make for amazing hands-on learning. Challenge your 4th grade students to build an elevator that can safely lift a certain amount of weight.

Make a model seismometer

Paper cup suspended by strings, with a marker sticking out the bottom making lines on a strip of paper

Explore the science of seismology and learn how scientists study earthquakes and their effects. This model seismometer is easy to build and fun to experiment with.

Learn more: Model Seismometer at Science Sparks

Conduct an egg drop

Here’s one more classic to add to our list of 4th grade science experiments: the egg drop! The great thing about this project is that kids can do it at any age, with different materials and heights to mix it up. Hit the link below to get an egg drop project designed just for 4th graders.

Learn more: Egg Drop Challenge Ideas

Demonstrate Newton’s laws of motion with balloon rockets

Who doesn’t love balloon rockets?! Your students will have a blast(off) displaying Newton’s third law of motion while learning about physics.

Many 4th grade science standards include units on energy and motion. These energy science activities offer cool hands-on ways to spice up your classroom lessons.

Flick marbles to learn transfer of energy

Fourth grade science student flicking a marble along the ridge in a ruler

This experiment is a bit of a thinker: What will happen when one moving marble hits several stationary marbles sitting in a row? Flick the first marble and find out!

Learn more: Marble Energy Transfer at Frugal Fun for Boys and Girls

See energy transfer in action with sports balls

Place a tennis ball on top of a basketball and bounce them together to see how energy transfers from one object to another. This one is very easy, and kids will love seeing how high they can get the balls to bounce!

Go an on energy scavenger hunt

A printable energy scavenger hunt on bright green paper against a blue background

Emphasize the fact that energy is all around us in one form or another with this easy, free printable energy science activity. For a more advanced version, help students identify each kind of energy (kinetic, stored, heat, etc.) they find.

Learn more: Energy Scavenger Hunt at The Science Penguin

See a heat-powered windmill demonstrate convection

Heat rises, and its interaction with cooler air creates convection currents. Find out how we can put convection to work for us with this 4th grade science craft project.

Capture waves in a bottle

Plastic bottle with blue water and a toy ship inside

Here’s a quick and easy way to show wave action in a no-mess way. You don’t need to add a little ship to the bottle, but it does make it more fun!

Learn more: Waves in a Bottle at What I Have Learned Teaching

Assemble a wave machine

Turn this one into a class cooperative activity, or try it as a science fair project idea. Either way, it’s an incredibly fascinating way to demonstrate the energy science of waves.

Use a Slinky to demonstrate types of waves

A Slinky is more than just a toy—it’s also a terrific science manipulative! Use it to see waves in motion, both longitudinal and transverse.

Watch gravity beads prove Newton’s laws

Child holding a cup of blue bead strings, watching them flow out of the cup

You’ll need a loooooooong string of beads for this experiment. Make your own by taping dollar-store strings together, or buy a long bead garland . Pile them in a cup and get the beads going; it’s fascinating to watch inertia and gravity at work.

Learn more: Gravity Beads at Teach Beside Me

Spin marble tops to learn about inertia

Colorful marbles glued together in several pyramidal shapes

Glue together marbles in a variety of pyramidal patterns to form tops, then form hypotheses about which will spin best. Afterwards, kids will have fun new toys to play with!

Learn more: Marble Tops at KidsActivities.com

Visualize the second law of motion with soda cans

Newton’s second law, concerning acceleration, force, and mass, can be a little hard to understand. This easy 4th grade science demo makes it a little easier to visualize.

More 4th Grade Science Projects and Activities

Use these cool science experiments to encourage a love of science, at home or in the classroom!

Measure a magnet’s attraction force

Small magnet, paper clip, ruler, and instruction card

Fourth grade science students already know that magnets attract metal objects. In this experiment, they’ll measure to see how close a magnet needs to be to an object for the attraction to work. Mix things up with different sizes of magnets and objects of various weights.

Learn more: Magnet Measurements at Ashleigh’s Education Journey

See light refraction in action

Student dipping a drawing into a glass of water, using light refraction to make the color disappear

This seems more like a magic trick, but we promise it’s science! Make colors seem to appear and disappear, change numbers into letters, and more.

Learn more: Light Refraction at Ronyes Tech

“Draw” on water with dry-erase marker

This is another one of those mind-blowing science demos that kids will want to try over and over again. Draw on a shallow bowl or plate with dry-erase markers , then slowly add water. The marker (which is insoluble in water) will float to the top!

Paint with sunscreen

Sun painted onto a piece of black construction paper using sunscreen

Prove that sunscreen really does provide protection from harmful UV rays. Turn this into a full-blown experiment by trying different SPFs or comparing it to other creams or lotions without SPF.

Learn more: Paint With Sunscreen at Team Cartwright

Become human sundials

Fourth grade science students measuring their outlines drawn in sidewalk chalk on the playground

Choose a sunny day and grab some sidewalk chalk—your students are about to become sundials! They’ll practice measuring skills and learn about the movement of the sun across the sky.

Learn more: Human Sundial at Rhythms of Play

Mine for chocolate chips

Student's hand digging through a crumbled cookie to pull out chocolate chips

If you’re learning about mineral resources, this quick hands-on activity is an interesting way to explore the effects of mining. Kids have two minutes to find as many chocolate chips as they can in a cookie. Will they smash it up and destroy it entirely? Pick them out one by one? This experiment can lead to intriguing discussions.

Learn more: Mining for Chocolate Chips at Sarah’s STEM Stuff

Assemble an edible DNA model

Student holding a DNA model made from Twizzlers, colored marshmallows, and toothpicks

Use licorice sticks, four different-colored candies or fruits, and toothpicks to build an edible strand of DNA. Learn about chemical bonds and the helix shape, then eat your creation!

Learn more: Edible DNA Model at wikiHow

Layer an edible soil model

Clear cup layered with chocolate chip bedrock, pudding subsoil, crushed cookie topsoil, and coconut grass

Digging in the dirt is fun, but it’s even more fun when you can eat the dirt when you’re finished! Create edible soil-layer models, complete with gummy worms, for a simple earth science project. ( Find more edible science projects here. )

Learn more: Edible Soil Layers at Super Teacher Blog

Turn a penny green

Five pennies turned various shades of green

Experiment with simple chemical reactions as you turn pennies green using vinegar. (Don’t forget to tell students that the Statue of Liberty is green for this very same reason!)

Learn more: Penny Reactions at Buggy and Buddy

Use marshmallows to explore Boyle’s law

Fourth grade science students holding large syringes filled with colorful marshmallows

Seeing Boyle’s law (which relates pressure and volume of gasses) in action makes it a little easier to understand and remember. This simple 4th grade science experiment uses marshmallows to make a great visual.

Learn more: Boyle’s Law at Hojo’s Teaching Adventures

Form ocean currents

Glass pan full of blue and purple swirls of water, with ice cubes and plastic sea creatures

Learning about oceanography? Demonstrate how ocean currents form using warm and cold water (and a few plastic sea creatures for extra fun!).

Learn more: Ocean Currents at Life Over C’s

Understand the impact of non-renewable resources

Index cards with various pasta types glued to them, including rotini, rigatoni, and shells

This is a neat Earth Day activity . Discuss the differences between renewable and non-renewable resources, then have your class form “companies” to “mine” non-renewable resources. As they compete, they’ll see how quickly the resources are used. It’s a great tie-in to energy conservation discussions.

Learn more: Non-Renewable Resources at The Owl Teacher

Explore blood components

Glass jars full of corn syrup, red candy, and marshmallows

Use simple kitchen supplies to create a jar full of “blood” that includes plasma, platelets, red blood cells, and white blood cells. (You can even snack on the blood cells along the way!)

Learn more: Blood Model at Almost Supermom

Create cool colors with candy

Learn about diffusion in the sweetest way! Grab a bag of Skittles for this quick and easy 4th grade science project.

Wow them with glowing water

Three bottles of water, one clear, one glowing blow, and one glowing green

Your students will ooh and aah at the result of this exploratory way to show phosphors in action with a black light, different types of water, and a highlighter. The results of this experiment might surprise both you and your students!

Learn more: Glowing Water Experiment at Cool Science Experiments Headquarters

Keep the STEM excitement going with these 25 Fantastic Free 4th Grade Math Games .

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Whether you need 4th grade science fair project ideas or are a teacher looking for engaging experiments for the classroom, find them here!

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