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Okay, this is the hardest part of the whole project…picking your topic. But here are some ideas to get you started. Even if you don’t like any, they may inspire you to come up with one of your own. Remember, check all project ideas with your teacher and parents, and don’t do any project that would hurt or scare people or animals. Good luck!

• Does music affect on animal behavior?
• Does the color of food or drinks affect whether or not we like them?
• Where are the most germs in your school? ( CLICK for more info. )
• Does music have an affect on plant growth?
• Which kind of food do dogs (or any animal) prefer best?
• Which paper towel brand is the strongest?
• What is the best way to keep an ice cube from melting?
• What level of salt works best to hatch brine shrimp?
• Can the food we eat affect our heart rate?
• How effective are child-proof containers and locks.
• Can background noise levels affect how well we concentrate?
• Does acid rain affect the growth of aquatic plants?
• What is the best way to keep cut flowers fresh the longest?
• Does the color of light used on plants affect how well they grow?
• What plant fertilizer works best?
• Does the color of a room affect human behavior?
• Do athletic students have better lung capacity?
• What brand of battery lasts the longest?
• Does the type of potting soil used in planting affect how fast the plant grows?
• What type of food allow mold to grow the fastest?
• Does having worms in soil help plants grow faster?
• Can plants grow in pots if they are sideways or upside down?
• Does the color of hair affect how much static electricity it can carry? (test with balloons)
• How much weight can the surface tension of water hold?
• Can some people really read someone else’s thoughts?
• Which soda decays fallen out teeth the most?
• What light brightness makes plants grow the best?
• Does the color of birdseed affect how much birds will eat it?
• Do natural or chemical fertilizers work best?
• Can mice learn? (you can pick any animal)
• Can people tell artificial smells from real ones?
• What brands of bubble gum produce the biggest bubbles?
• Does age affect human reaction times?
• What is the effect of salt on the boiling temperature of water?
• Does shoe design really affect an athlete’s jumping height?
• What type of grass seed grows the fastest?
• Can animals see in the dark better than humans?

Didn’t see one you like? Don’t worry…look over them again and see if they give you an idea for your own project that will work for you. Remember, find something that interests you, and have fun with it.

To download and print this list of ideas CLICK HERE .

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• a little helpful advice

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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

Do a Science Fair Project!

How do you do a science fair project.

Ask a parent, teacher, or other adult to help you research the topic and find out how to do a science fair project about it.

Test, answer, or show?

Your science fair project may do one of three things:

Test an idea (or hypothesis.)

Answer a question.

Show how nature works.

Topic ideas:

Space topics:.

How do the constellations change in the night sky over different periods of time?

How does the number of stars visible in the sky change from place to place because of light pollution?

Learn about and demonstrate the ancient method of parallax to measure the distance to an object, such as stars and planets.

Study different types of stars and explain different ways they end their life cycles.

Earth topics:

How do the phases of the Moon correspond to the changing tides?

Demonstrate what causes the phases of the Moon?

How does the tilt of Earth’s axis create seasons throughout the year?

How do weather conditions (temperature, humidity) affect how fast a puddle evaporates?

How salty is the ocean?

Solar system topics:

How does the size of a meteorite relate to the size of the crater it makes when it hits Earth?

How does the phase of the Moon affect the number of stars visible in the sky?

Show how a planet’s distance from the Sun affects its temperature.

Sun topics:

Observe and record changes in the number and placement of sun spots over several days. DO NOT look directly at the Sun!

Make a sundial and explain how it works.

Show why the Moon and the Sun appear to be the same size in the sky.

How effective are automobile sunshades?

Study and explain the life space of the sun relative to other stars.

Pick a topic.

Try to find out what people already know about it.

State a hypothesis related to the topic. That is, make a cause-and-effect-statement that you can test using the scientific method .

Explain something.

Make a plan to observe something.

Design and carry out your research, keeping careful records of everything you do or see.

Create an exhibit or display to show and explain to others what you hoped to test (if you had a hypothesis) or what question you wanted to answer, what you did, what your data showed, and your conclusions.

Write a short report that also states the same things as the exhibit or display, and also gives the sources of your initial background research.

Practice describing your project and results, so you will be ready for visitors to your exhibit at the science fair.

Follow these steps to a successful science fair entry!

If you liked this, you may like:

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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50 of the Best Science Fair Project Ideas for Kids

• February 10, 2021

So you have a science fair coming up at school and want to make a project that’s sure to win a prize ribbon? Well, you’ve come to the right place. Choosing the right project requires plenty of research. That’s why we’ve rounded up the best science fair projects ideas to help you along your search.

50 STEM Experiment Ideas for Kids

These 50 science fair project ideas are all great for kids- early and older elementary school students, with a few suitable for middle school students as well. Make a topic that fascinates you, come up with a hypothesis, and see what happens next!

Plus, once you’ve chosen your topic, use this science fair project how-to video from NASA as a helpful guide.

Important note: Some of these science fair projects require the help or supervision of an adult. Always make sure an older family member is nearby and knows what you’re doing as you work on these projects.

1. With this science fair experiment , you can learn what factors affect melting ice.

2. Try this magic milk experiment for an easy science fair project that younger students can accomplish.

3. How much sun does a seed need to sprout? Discover the answer by trying this project you can easily complete from home.

4. Build your own water clock and see how well you can get it to measure time.

5. If you’re interested in a little microbiology, try out this egg cell experiment .

6. What’s the best way to prevent apples from browning? Find out for yourself and make sure to record the results.

7. Do birds eat more food if it is a certain color? Find out with this intriguing experiment .

8. Discover how clouds turn water vapors into rain and diagram a few common types of clouds through this kid-friendly science fair project .

9. Make your own plant cell model using styrofoam and playdough.

10. Learn about aerodynamics by experimenting with paper airplane shapes and seeing which one flies best.

11. Learn how to accelerate the rusting process with this quick and thought-provoking science project .

12. Want to learn about water and density for your project? Perform this floating egg experiment and try out the follow-up questions at the bottom.

13. This project about bending light is perfect for older elementary school students who want to dip their toes into physics.

14. This biology-based science experiment asks, “Will plants grow towards a specific light source?”

15. Learn about greenhouse gases with this science fair idea .

16. Experiment with what makes fruit ripen quickly and write down your results to present at your science fair.

17. Use this hands-on experiment to explore how carbonated drinks affect teeth.

18. Which factors affect evaporation? Find out for yourself with this project that’s perfect for students who can complete it with a little adult supervision.

19. Find out which types of toothpaste work the best and, after measuring your results, try and come up with a conclusion.

20. If the weather is warm out during your science fair, try building a solar oven .

21. For a simple chemistry project , you can make sugar crystals and see what material works best for growing them.

22. Which common material is the best heat conductor? Find out with this science fair project that can be done with adult supervision, as it needs boiling water.

23. Craft your own thermos bottle and test it out for a project all about insulation.

24. Make a DIY thermometer and test it out for a practical and hands-on science project.

25. Try this celery experiment to learn how plant capillaries work.

26. How does the air temperature affect movement? Try one of these fun science fair project ideas as a model for your own experiment.

27. If you’re passionate about the environment, try this recycling experiment for your science fair project

28. How does paint color affect drying time? Make your predictions and test it out for yourself.

29. Learn which soil is best for growing tomatoes if your science fair takes place during warm weather.

30. Build your own lemon battery and see if you can get it to work to learn about electricity.

31. If you want to try the epitome of science fair projects, try making a science fair volcano.

32. How much sugar is in different popular foods? If you’re interested in health science, try this fascinating experiment .

33. If you’d rather look at prompts and create your own project, use these science fair questions for inspiration.

34. Does music affect plant growth? Discover for yourself with this project .

35. Do you need science fair project ideas that will encourage others to recycle? Learn about how to make your own paper .

36. If you have a few furry friends in your neighborhood, consider testing if dogs are colorblind with this project .

37. How does temperature affect air pressure in a ball? Find out the answer with this sporty science project .

38. Build your own pulley and see what kinds of objects you can make it carry.

39. Learn a little about chemistry with this science fair experiment that asks which paper towels are the most absorbent.

40. What is the dirtiest spot in the average home? Find the answer by cultivating bacteria growth in this experiment .

41. Discover how to test thermal energy by observing water temperature.

42. Can you grow seeds with liquids other than water? Find out with this kid-friendly science experiment .

43. This Sun or Shade science fair projec t is perfect for elementary school students.

44. This cool science fair project asks an intriguing question about insect biology: what sweetener do ants prefer?

45. Make a working model of lungs for a science fair project that’s sure to fascinate.

46. Want to try a science fair project that can only end with tasty treats? Bake some cookies and try one of these sweet experiments .

47. Interested in astronomy? Try out this experiment that teaches why the moon’s shape seems to change every day.

48. What are the effects of disinfectant on germs? Use this science fair project as inspiration for your own.

49. Put your math skills to the test with this science fair project centered around the game tic tac toe.

50. What’s stronger: magnetism or gravity? Find out with this science fair experiment that’s perfect for early elementary students.

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High School Science Experiment Ideas

• Projects & Experiments
• Chemical Laws
• Periodic Table
• Scientific Method
• Biochemistry
• Physical Chemistry
• Medical Chemistry
• Chemistry In Everyday Life
• Famous Chemists
• Activities for Kids
• Abbreviations & Acronyms
• Weather & Climate
• Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
• B.A., Physics and Mathematics, Hastings College

Try these ideas for science experiments targeted at the high school educational level. Perform a science experiment and explore different  hypotheses to test.

Caffeine Experiments

JGI / Jamie Grill / Getty Images

You've probably heard that caffeine acts as a stimulant and may increase your concentration when you are under its influence. You can test this with an experiment.

Sample Hypothesis:

• Caffeine use does not affect typing speed .
• Caffeine does not affect concentration.

Student Conformity Experiments

Caiaimage / Sam Edwards / Getty Images

You are in a large group of students and the instructor asks the class what 9 x 7 is. One student says it is 54. So does the next. Do you fully trust your answer of 63? We are influenced by the beliefs of the people around us and sometimes conform to what the group believes. You can study the degree to which social pressure affects conformity.

• The number of students will not affect student conformity.
• Age does not affect student conformity.
• Gender has no effect on student conformity.

Smoke Bomb Experiments

Georgi Fadejev / EyeEm / Getty Images

Smoke bombs are fun for kids of all ages but are probably not appropriate experiment subjects for kids younger than high school level. Smoke bombs offer an interesting way to learn about combustion. They can be used as propellants in rockets, too.

• The ratio of smoke bomb ingredients will not affect the quantity of smoke that is produced.
• The ratio of ingredients will not affect the range of a smoke bomb rocket.

Hand Sanitizer Experiments

Elenathewise / Getty Images

Hand sanitizer is supposed to keep germs under control on your hands. You can culture bacteria to see if hand sanitizer is effective. You can compare different types of hand sanitizer to see if one works better than another. Can you make an effective natural hand sanitizer? Is hand sanitizer biodegradable?

• There is no difference in the effectiveness of different hand sanitizers.
• Hand sanitizer is biodegradable.
• There is no difference in effectiveness between homemade hand sanitizer and commercial hand sanitizer.
• Null Hypothesis Examples
• Middle School Science Experiments
• Examples of Independent and Dependent Variables
• Difference Between Independent and Dependent Variables
• High School Science Fair Projects
• Mosquito Bite Home Remedies
• Scientific Method Vocabulary Terms
• Cool Halloween Jack o Lanterns
• Do Hand Sanitizers Work Better Than Soap and Water?
• Stove Top Frozen Pizza Science Experiment
• Smoke Bomb Safety Information
• Chemistry Science Fair Project Ideas
• Science Projects for Every Subject
• Middle School Science Fair Project Ideas
• Science Experiments and Activities for Preschoolers
• Safe Science Experiments

100+ Easy & FUN Science Fair Project Ideas

This post may contain affiliate links.

Looking for FUN   science projects for kids ? Science is one of our favorite subjects around here. I have a huge list of over 100 easy science experiments for kids. You can use these classic science fair ideas when helping your child create their next science fair project. Kids will love these fun projects and experiments!

See my Scientific Method Worksheets and Posters to help teach the process of the scientific method including these 6 steps:

• Ask a question
• Make a hypothesis
• Record Data

These science fair project ideas can be used for may grade levels including elementary school aged kids, middle school aged kids and some would even work for high school. Many of these science activities are quick and easy to put together and will not break the bank either.

I divided the science fair project ideas out the best I could by topic and category for you. That way if there is a certain interest, you can find just what you are looking for. You will find science fair experiment ideas in biology, physics, chemistry, electricity, magnetism, earth science, and more!

All of these simple experiment ideas can be used in some way to create an awesome science fair project. Most are from my site, but many are from some other great bloggers! Click the links to get instructions and demonstrations on how these projects work.

Want more ideas? See also my post with 200 + Elementary STEM Projects .

Easy Energy and Physics Science Fair Projects

Kinetic Energy with Rubber Band Boats – this science project is a blast to create with kids!

Kinetic Energy- Shooting Star Spinner – This is a fun one on kinetic and potential energy

Kinetic Energy Gravity Spinner  – Do this experiment to show gravity!

Perpetual Motion Candle See Saw – This is a cool way to learn about motion!

How Does a String Telephone Work?  ~Raising Life Long Learners

Which Cup Will Keep Water Cold the Longest?  ~ Really, Are you Serious?

Light Refraction Science Experiment  ~ Look We’re Learning

Heat Conduction Experiment  ~ Look We’re Learning

Color Changing Sensory Bottle  ~ The Science Kiddo

Exploring Magnetic Fields

Magnet Pendulum

Levitating Magnets

Train Chain Reactions

Static Electricity Slime

What are Electrolytes?

Color and Light Reflection and Refraction Experiments

Simple Machines- Gears

Light Box Magic  ~ True Aim Education

Balloon Air Pressure Experiment  ~ Darcy and Brian

Make A Giant Catapult

Technology & Mechanical Science Projects for Kids

Is it Conductive? – test different objects to see if they conduct electricity.

How to Make a Coin Battery  – use coins to power a light!

How to Make a Lemon Battery – the power of lemon juice is pretty amazing.

What to Make a Dirt Battery – a battery out of dirt?  yup!

How do you Make a Potato Battery? ~from STEAM Powered Family

How to Make a Hydraulic Elevator ~ Make a water powered elevator

How to Make a Bubble Blower Machine

Paper Circuits – learn about circuits and electricity with this simple project.

Solar Powered Lego Car – harness the power of the sun!

Make an EASY Water Pump Sprinkler

Chemistry Science Projects for Kids With Chemical Reactions

Cabbage Juice pH Experiment – test different chemicals and substances to see their pH levels.

How too Make an Erupting Volcano (with salt dough)

How Do you Clean Pennies?

Why Do Baking Soda and Vinegar React?

How to Make Dry Ice Bubbles

Does it Dissolve?

How Do you Grow Crystals? (borax crystals)

Elephant Toothpaste with Two Types of Peroxide

What is Non-Newtonian Fluid?  (Oobleck Experiments)

Does it Rust? Oxidation Experiment

Rainbow Absorption

Film Canister Rockets

Blooming Paper Flowers

Dancing Acorns  ~ Hands-on Teaching Ideas

States of Matter Experiments – solids, liquids and gases

Rubber Bouncing Egg Experiment

Color Changing Flowers Experiment  ~ Messy Little Monster

Paper Burning Experiment  ~ Preschool Powol Packets

How to Make a Paper Mache Erupting Volcano  ~ Red Ted Art

Mentos and Soda Geysers

Anatomy Science Fair Projects

How Do Ears Work?

Play Dough Anatomy

Animal Digestion Experiment  ~ Schooling a Monkey

Why We Need Muscles & Bones  ~ I Can Teach My Child

How Do Lungs Work?   ~ Sciene Sparks

DNA Experiment

Earth Science and Nature Science Fair Projects

How do Earthquakes Happen ?

Can You Build a House to Resist an Earthquake?

Make your Own Crystal Rock Candy Geodes

What are Convection Currents?

Study surface tension with Water Strider Insects

How are Rainbows made?

How to Clean Dirty Water

Geology Experiment: Stalactites and Stalagmites Formation

What’s In My Water? 

What are Shells Made of?

How Can We Stay Dry During the Rain  ~ Pink Stripey Socks

What Surfaces in my House are the Dirtiest? Mold Science

Density Experiment with different liquids, also tests buoyancy!

Why Do Leaves Change Colors? Leaf Chromatography Experiment

Rising Tide Experiment

Soda Bottle Compost  ~ Busy Mommy Media

Build a Sun Shelter  ~ Buggy and Buddy

Hurricane Model Experiment  ~Preschool Powol Packets

Easy Condensation Experiment  – Look We’re Learning

Salt Water Density Experiment  ~ The Science Kiddo

Plant Science- Observing Bulb Growth  ~Buggy and Buddy

How to Make a Compass  ~ Parenting Chaos

Why do Pinecones Open & Close?  ~ Parenting Chaos

Leaf Transpiration Experiment – how leaves breathe, use a plastic bag to collect the moisture from a tree.

Pumpkin Petri Dishes  ~ Hands-on Teaching Ideas

Rainy Day Science – learn about filtering rain water

Making a Solar Still – harness the power of the sun with this cool science experiment!

Make Your Own Human Sun Dial

How are Sedimentary Rocks & Fossils Made? 

How Do Sharks Float?  ~ Preschool Powol Packets

How to Make Square Bubbles

What Soil is Best for Growing Seeds?  ~ Schooling a Monkey

Simple Food Science Fair Project Ideas

Want a food-based science fair project?  These ideas are fun and edible, too!  Who doesn’t love learning with food?

Food Science: Make a Loaf of Bread in a Bag

Why Does Gelatin Not Set with Certain Fruits ?

What Foods will Grow the most Mold?

Cake Chemistry Experiment

Popcorn and Salt Science Experiment  ~ Awe Filled Homemaker

What Prevents Apples from Browning?

How to Make Plastic with Gelatin  ~ STEAM Powered Family

Melting Ice Science Experiment  ~ The Chaos and the Clutter

Pie Crust Experiment

Food Chemistry~ Turn Juice into Noodles !

Green Eggs Food Chemistry (no food coloring required!)

How Strong are Eggs?  ~ Hands-On Teaching Ideas

Make Solar S’mores

Hot Chocolate Science Experiment  ~ Creative Family Fun

Bread Mold Science Project  ~ Schooling a Monkey

Other Fun & Easy Science Project Ideas

Toilet Paper Comparisons   ~ Pink Stripey Socks

Egg Drop Challenge 

Press n’ Seal vs. Saran Wrap

Hockey Science Experiment  ~ Creative Family Fun

I hope you found an idea that will work for your little scientists next science fair project. I’d love to hear what you did and see pictures of the finished project!

Former school teacher turned homeschool mom of 4 kids. Loves creating awesome hands-on creative learning ideas to make learning engaging and memorable for all kids!

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Understanding Science

How science REALLY works...

• Understanding Science 101
• Misconceptions
• Testing ideas with evidence from the natural world is at the core of science.
• Scientific testing involves figuring out what we would  expect  to observe if an idea were correct and comparing that expectation to what we  actually  observe.
• Scientific arguments are built from an idea and the evidence relevant to that idea.
• Scientific arguments can be built in any order. Sometimes a scientific idea precedes any evidence relevant to it, and other times the evidence helps inspire the idea.

Misconception:  Science proves ideas.

Misconception:  Science can only disprove ideas.

Correction:  Science neither proves nor disproves. It accepts or rejects ideas based on supporting and refuting evidence, but may revise those conclusions if warranted by new evidence or perspectives.  Read more about it.

The core of science: Relating evidence and ideas

In this case, the term  argument  refers not to a disagreement between two people, but to an evidence-based line of reasoning — so scientific arguments are more like the closing argument in a court case (a logical description of what we think and why we think it) than they are like the fights you may have had with siblings. Scientific arguments involve three components: the idea (a  hypothesis  or theory), the  expectations  generated by that idea (frequently called predictions), and the actual observations relevant to those expectations (the evidence). These components are always related in the same logical way:

• What would we expect to see if this idea were true (i.e., what is our expected observation)?
• What do we actually observe?
• Do our expectations match our observations?

PREDICTIONS OR EXPECTATIONS?

When scientists describe their arguments, they frequently talk about their expectations in terms of what a hypothesis or theory predicts: “If it were the case that smoking causes lung cancer, then we’d  predict  that countries with higher rates of smoking would have higher rates of lung cancer.” At first, it might seem confusing to talk about a prediction that doesn’t deal with the future, but that refers to something going on right now or that may have already happened. In fact, this is just another way of discussing the expectations that the hypothesis or theory generates. So when a scientist talks about the  predicted  rates of lung cancer, he or she really means something like “the rates that we’d expect to see if our hypothesis were correct.”

If the idea generates expectations that hold true (are actually observed), then the idea is more likely to be accurate. If the idea generates expectations that don’t hold true (are not observed), then we are less likely to  accept  the idea. For example, consider the idea that cells are the building blocks of life. If that idea were true, we’d expect to see cells in all kinds of living tissues observed under a microscope — that’s our expected observation. In fact, we do observe this (our actual observation), so evidence supports the idea that living things are built from cells.

Though the structure of this argument is consistent (hypothesis, then expectation, then actual observation), its pieces may be assembled in different orders. For example, the first observations of cells were made in the 1600s, but cell theory was not postulated until 200 years later — so in this case, the evidence actually helped inspire the idea. Whether the idea comes first or the evidence comes first, the logic relating them remains the same.

Here, we’ll explore scientific arguments and how to build them. You can investigate:

Putting the pieces together: The hard work of building arguments

• Predicting the past
• Arguments with legs to stand on

Or just click the  Next  button to dive right in!

• Take a sidetrip
• Teaching resources

Scientific arguments rely on testable ideas. To learn what makes an idea testable, review our  Science Checklist .

• Forming hypotheses — scientific explanations — can be difficult for students. It is often easier for students to generate an expectation (what they think will happen or what they expect to observe) based on prior experience than to formulate a potential explanation for that phenomena. You can help students go beyond expectations to generate real, explanatory hypotheses by providing sentence stems for them to fill in: “I expect to observe A because B.” Once students have filled in this sentence you can explain that B is a hypothesis and A is the expectation generated by that hypothesis.
• You can help students learn to distinguish between hypotheses and the expectations generated by them by regularly asking students to analyze lecture material, text, or video. Students should try to figure out which aspects of the content were hypotheses and which were expectations.

Summing up the process

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72 Easy Science Experiments Using Materials You Already Have On Hand

Because science doesn’t have to be complicated.

If there is one thing that is guaranteed to get your students excited, it’s a good science experiment! While some experiments require expensive lab equipment or dangerous chemicals, there are plenty of cool projects you can do with regular household items. We’ve rounded up a big collection of easy science experiments that anybody can try, and kids are going to love them!

Easy Chemistry Science Experiments

Easy physics science experiments, easy biology and environmental science experiments, easy engineering experiments and stem challenges.

1. Taste the Rainbow

Teach your students about diffusion while creating a beautiful and tasty rainbow! Tip: Have extra Skittles on hand so your class can eat a few!

Learn more: Skittles Diffusion

2. Crystallize sweet treats

Crystal science experiments teach kids about supersaturated solutions. This one is easy to do at home, and the results are absolutely delicious!

Learn more: Candy Crystals

3. Make a volcano erupt

This classic experiment demonstrates a chemical reaction between baking soda (sodium bicarbonate) and vinegar (acetic acid), which produces carbon dioxide gas, water, and sodium acetate.

Learn more: Best Volcano Experiments

4. Make elephant toothpaste

This fun project uses yeast and a hydrogen peroxide solution to create overflowing “elephant toothpaste.” Tip: Add an extra fun layer by having kids create toothpaste wrappers for plastic bottles.

5. Blow the biggest bubbles you can

Add a few simple ingredients to dish soap solution to create the largest bubbles you’ve ever seen! Kids learn about surface tension as they engineer these bubble-blowing wands.

Learn more: Giant Soap Bubbles

6. Demonstrate the “magic” leakproof bag

All you need is a zip-top plastic bag, sharp pencils, and water to blow your kids’ minds. Once they’re suitably impressed, teach them how the “trick” works by explaining the chemistry of polymers.

Learn more: Leakproof Bag

7. Use apple slices to learn about oxidation

Have students make predictions about what will happen to apple slices when immersed in different liquids, then put those predictions to the test. Have them record their observations.

Learn more: Apple Oxidation

8. Float a marker man

Their eyes will pop out of their heads when you “levitate” a stick figure right off the table! This experiment works due to the insolubility of dry-erase marker ink in water, combined with the lighter density of the ink.

Learn more: Floating Marker Man

9. Discover density with hot and cold water

There are a lot of easy science experiments you can do with density. This one is extremely simple, involving only hot and cold water and food coloring, but the visuals make it appealing and fun.

Learn more: Layered Water

10. Layer more liquids

This density demo is a little more complicated, but the effects are spectacular. Slowly layer liquids like honey, dish soap, water, and rubbing alcohol in a glass. Kids will be amazed when the liquids float one on top of the other like magic (except it is really science).

Learn more: Layered Liquids

11. Grow a carbon sugar snake

Easy science experiments can still have impressive results! This eye-popping chemical reaction demonstration only requires simple supplies like sugar, baking soda, and sand.

Learn more: Carbon Sugar Snake

12. Mix up some slime

Tell kids you’re going to make slime at home, and watch their eyes light up! There are a variety of ways to make slime, so try a few different recipes to find the one you like best.

13. Make homemade bouncy balls

These homemade bouncy balls are easy to make since all you need is glue, food coloring, borax powder, cornstarch, and warm water. You’ll want to store them inside a container like a plastic egg because they will flatten out over time.

Learn more: Make Your Own Bouncy Balls

14. Create eggshell chalk

Eggshells contain calcium, the same material that makes chalk. Grind them up and mix them with flour, water, and food coloring to make your very own sidewalk chalk.

Learn more: Eggshell Chalk

15. Make naked eggs

This is so cool! Use vinegar to dissolve the calcium carbonate in an eggshell to discover the membrane underneath that holds the egg together. Then, use the “naked” egg for another easy science experiment that demonstrates osmosis .

Learn more: Naked Egg Experiment

16. Turn milk into plastic

This sounds a lot more complicated than it is, but don’t be afraid to give it a try. Use simple kitchen supplies to create plastic polymers from plain old milk. Sculpt them into cool shapes when you’re done!

17. Test pH using cabbage

Teach kids about acids and bases without needing pH test strips! Simply boil some red cabbage and use the resulting water to test various substances—acids turn red and bases turn green.

Learn more: Cabbage pH

18. Clean some old coins

Use common household items to make old oxidized coins clean and shiny again in this simple chemistry experiment. Ask kids to predict (hypothesize) which will work best, then expand the learning by doing some research to explain the results.

Learn more: Cleaning Coins

19. Pull an egg into a bottle

This classic easy science experiment never fails to delight. Use the power of air pressure to suck a hard-boiled egg into a jar, no hands required.

Learn more: Egg in a Bottle

20. Blow up a balloon (without blowing)

Chances are good you probably did easy science experiments like this when you were in school. The baking soda and vinegar balloon experiment demonstrates the reactions between acids and bases when you fill a bottle with vinegar and a balloon with baking soda.

21 Assemble a DIY lava lamp

This 1970s trend is back—as an easy science experiment! This activity combines acid-base reactions with density for a totally groovy result.

22. Explore how sugary drinks affect teeth

The calcium content of eggshells makes them a great stand-in for teeth. Use eggs to explore how soda and juice can stain teeth and wear down the enamel. Expand your learning by trying different toothpaste-and-toothbrush combinations to see how effective they are.

Learn more: Sugar and Teeth Experiment

23. Mummify a hot dog

If your kids are fascinated by the Egyptians, they’ll love learning to mummify a hot dog! No need for canopic jars , just grab some baking soda and get started.

24. Extinguish flames with carbon dioxide

This is a fiery twist on acid-base experiments. Light a candle and talk about what fire needs in order to survive. Then, create an acid-base reaction and “pour” the carbon dioxide to extinguish the flame. The CO2 gas acts like a liquid, suffocating the fire.

25. Send secret messages with invisible ink

Turn your kids into secret agents! Write messages with a paintbrush dipped in lemon juice, then hold the paper over a heat source and watch the invisible become visible as oxidation goes to work.

Learn more: Invisible Ink

26. Create dancing popcorn

This is a fun version of the classic baking soda and vinegar experiment, perfect for the younger crowd. The bubbly mixture causes popcorn to dance around in the water.

27. Shoot a soda geyser sky-high

You’ve always wondered if this really works, so it’s time to find out for yourself! Kids will marvel at the chemical reaction that sends diet soda shooting high in the air when Mentos are added.

Learn more: Soda Explosion

28. Send a teabag flying

Hot air rises, and this experiment can prove it! You’ll want to supervise kids with fire, of course. For more safety, try this one outside.

Learn more: Flying Tea Bags

29. Create magic milk

This fun and easy science experiment demonstrates principles related to surface tension, molecular interactions, and fluid dynamics.

Learn more: Magic Milk Experiment

30. Watch the water rise

Learn about Charles’s Law with this simple experiment. As the candle burns, using up oxygen and heating the air in the glass, the water rises as if by magic.

Learn more: Rising Water

31. Learn about capillary action

Kids will be amazed as they watch the colored water move from glass to glass, and you’ll love the easy and inexpensive setup. Gather some water, paper towels, and food coloring to teach the scientific magic of capillary action.

Learn more: Capillary Action

32. Give a balloon a beard

Equally educational and fun, this experiment will teach kids about static electricity using everyday materials. Kids will undoubtedly get a kick out of creating beards on their balloon person!

Learn more: Static Electricity

33. Find your way with a DIY compass

Here’s an old classic that never fails to impress. Magnetize a needle, float it on the water’s surface, and it will always point north.

Learn more: DIY Compass

34. Crush a can using air pressure

Sure, it’s easy to crush a soda can with your bare hands, but what if you could do it without touching it at all? That’s the power of air pressure!

35. Tell time using the sun

While people use clocks or even phones to tell time today, there was a time when a sundial was the best means to do that. Kids will certainly get a kick out of creating their own sundials using everyday materials like cardboard and pencils.

Learn more: Make Your Own Sundial

36. Launch a balloon rocket

Grab balloons, string, straws, and tape, and launch rockets to learn about the laws of motion.

37. Make sparks with steel wool

All you need is steel wool and a 9-volt battery to perform this science demo that’s bound to make their eyes light up! Kids learn about chain reactions, chemical changes, and more.

Learn more: Steel Wool Electricity

38. Levitate a Ping-Pong ball

Kids will get a kick out of this experiment, which is really all about Bernoulli’s principle. You only need plastic bottles, bendy straws, and Ping-Pong balls to make the science magic happen.

39. Whip up a tornado in a bottle

There are plenty of versions of this classic experiment out there, but we love this one because it sparkles! Kids learn about a vortex and what it takes to create one.

Learn more: Tornado in a Bottle

40. Monitor air pressure with a DIY barometer

This simple but effective DIY science project teaches kids about air pressure and meteorology. They’ll have fun tracking and predicting the weather with their very own barometer.

Learn more: DIY Barometer

41. Peer through an ice magnifying glass

Students will certainly get a thrill out of seeing how an everyday object like a piece of ice can be used as a magnifying glass. Be sure to use purified or distilled water since tap water will have impurities in it that will cause distortion.

Learn more: Ice Magnifying Glass

42. String up some sticky ice

Can you lift an ice cube using just a piece of string? This quick experiment teaches you how. Use a little salt to melt the ice and then refreeze the ice with the string attached.

Learn more: Sticky Ice

43. “Flip” a drawing with water

Light refraction causes some really cool effects, and there are multiple easy science experiments you can do with it. This one uses refraction to “flip” a drawing; you can also try the famous “disappearing penny” trick .

Learn more: Light Refraction With Water

44. Color some flowers

We love how simple this project is to re-create since all you’ll need are some white carnations, food coloring, glasses, and water. The end result is just so beautiful!

45. Use glitter to fight germs

Everyone knows that glitter is just like germs—it gets everywhere and is so hard to get rid of! Use that to your advantage and show kids how soap fights glitter and germs.

Learn more: Glitter Germs

46. Re-create the water cycle in a bag

You can do so many easy science experiments with a simple zip-top bag. Fill one partway with water and set it on a sunny windowsill to see how the water evaporates up and eventually “rains” down.

Learn more: Water Cycle

47. Learn about plant transpiration

Your backyard is a terrific place for easy science experiments. Grab a plastic bag and rubber band to learn how plants get rid of excess water they don’t need, a process known as transpiration.

Learn more: Plant Transpiration

48. Clean up an oil spill

Before conducting this experiment, teach your students about engineers who solve environmental problems like oil spills. Then, have your students use provided materials to clean the oil spill from their oceans.

Learn more: Oil Spill

49. Construct a pair of model lungs

Kids get a better understanding of the respiratory system when they build model lungs using a plastic water bottle and some balloons. You can modify the experiment to demonstrate the effects of smoking too.

Learn more: Model Lungs

50. Experiment with limestone rocks

Kids  love to collect rocks, and there are plenty of easy science experiments you can do with them. In this one, pour vinegar over a rock to see if it bubbles. If it does, you’ve found limestone!

Learn more: Limestone Experiments

51. Turn a bottle into a rain gauge

All you need is a plastic bottle, a ruler, and a permanent marker to make your own rain gauge. Monitor your measurements and see how they stack up against meteorology reports in your area.

Learn more: DIY Rain Gauge

52. Build up towel mountains

This clever demonstration helps kids understand how some landforms are created. Use layers of towels to represent rock layers and boxes for continents. Then pu-u-u-sh and see what happens!

Learn more: Towel Mountains

53. Take a play dough core sample

Learn about the layers of the earth by building them out of Play-Doh, then take a core sample with a straw. ( Love Play-Doh? Get more learning ideas here. )

Learn more: Play Dough Core Sampling

54. Project the stars on your ceiling

Use the video lesson in the link below to learn why stars are only visible at night. Then create a DIY star projector to explore the concept hands-on.

Learn more: DIY Star Projector

55. Make it rain

Use shaving cream and food coloring to simulate clouds and rain. This is an easy science experiment little ones will beg to do over and over.

Learn more: Shaving Cream Rain

56. Blow up your fingerprint

This is such a cool (and easy!) way to look at fingerprint patterns. Inflate a balloon a bit, use some ink to put a fingerprint on it, then blow it up big to see your fingerprint in detail.

57. Snack on a DNA model

Twizzlers, gumdrops, and a few toothpicks are all you need to make this super-fun (and yummy!) DNA model.

Learn more: Edible DNA Model

58. Dissect a flower

Take a nature walk and find a flower or two. Then bring them home and take them apart to discover all the different parts of flowers.

59. Craft smartphone speakers

No Bluetooth speaker? No problem! Put together your own from paper cups and toilet paper tubes.

Learn more: Smartphone Speakers

60. Race a balloon-powered car

Kids will be amazed when they learn they can put together this awesome racer using cardboard and bottle-cap wheels. The balloon-powered “engine” is so much fun too.

Learn more: Balloon-Powered Car

61. Build a Ferris wheel

You’ve probably ridden on a Ferris wheel, but can you build one? Stock up on wood craft sticks and find out! Play around with different designs to see which one works best.

Learn more: Craft Stick Ferris Wheel

62. Design a phone stand

There are lots of ways to craft a DIY phone stand, which makes this a perfect creative-thinking STEM challenge.

63. Conduct an egg drop

Put all their engineering skills to the test with an egg drop! Challenge kids to build a container from stuff they find around the house that will protect an egg from a long fall (this is especially fun to do from upper-story windows).

Learn more: Egg Drop Challenge Ideas

64. Engineer a drinking-straw roller coaster

STEM challenges are always a hit with kids. We love this one, which only requires basic supplies like drinking straws.

Learn more: Straw Roller Coaster

65. Build a solar oven

Explore the power of the sun when you build your own solar ovens and use them to cook some yummy treats. This experiment takes a little more time and effort, but the results are always impressive. The link below has complete instructions.

Learn more: Solar Oven

66. Build a Da Vinci bridge

There are plenty of bridge-building experiments out there, but this one is unique. It’s inspired by Leonardo da Vinci’s 500-year-old self-supporting wooden bridge. Learn how to build it at the link, and expand your learning by exploring more about Da Vinci himself.

Learn more: Da Vinci Bridge

67. Step through an index card

This is one easy science experiment that never fails to astonish. With carefully placed scissor cuts on an index card, you can make a loop large enough to fit a (small) human body through! Kids will be wowed as they learn about surface area.

68. Stand on a pile of paper cups

Combine physics and engineering and challenge kids to create a paper cup structure that can support their weight. This is a cool project for aspiring architects.

Learn more: Paper Cup Stack

69. Test out parachutes

Gather a variety of materials (try tissues, handkerchiefs, plastic bags, etc.) and see which ones make the best parachutes. You can also find out how they’re affected by windy days or find out which ones work in the rain.

Learn more: Parachute Drop

70. Recycle newspapers into an engineering challenge

It’s amazing how a stack of newspapers can spark such creative engineering. Challenge kids to build a tower, support a book, or even build a chair using only newspaper and tape!

Learn more: Newspaper STEM Challenge

71. Use rubber bands to sound out acoustics

Explore the ways that sound waves are affected by what’s around them using a simple rubber band “guitar.” (Kids absolutely love playing with these!)

Learn more: Rubber Band Guitar

72. Assemble a better umbrella

Challenge students to engineer the best possible umbrella from various household supplies. Encourage them to plan, draw blueprints, and test their creations using the scientific method.

Learn more: Umbrella STEM Challenge

Plus, sign up for our newsletters to get all the latest learning ideas straight to your inbox.

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Why Do Trees Drop So Many Seeds One Year, and Then Hardly Any the Next?

A new paper suggests that plants may use slow seed years to prevent the spread of disease

A mighty oak covers the ground in piles of acorns. Squirrels gather them up, growing fat on the rich bounty and storing more of the seeds away for the winter.

If you live in the temperate Northern Hemisphere, this may be one of your most familiar natural scenes of autumn, because various species of both oak trees and squirrels are common and visible throughout that range. It represents a simple predator-prey model that ecologists have studied since the early days of their science. But those early scientists—and, long before them, Indigenous people—noticed something unusual about this scene. Some years, a glut of acorns fell, creating a squirrel’s paradise under every tree. Other years, almost none did.

Plants dropping most of their seeds together in one year, then taking years almost or completely off from seed production, is called “seed masting.” Oak trees are one example, but thousands of species of trees and other long-lived plants use this boom-and-bust strategy. The most common explanation has involved those hungry squirrels, birds and countless other species that eat acorns. Drop enough seeds at once, the theory says, and some will survive the predators’ feast. Ecologists call this the “predator satiation hypothesis,” and it has been a widely accepted explanation for seed masting for decades.

But predator satiation is far from the only theory. Another idea suggests masting helps insects like bees most efficiently pollinate a plant. If all of the trees of one species flower and set seed at once, that theory goes, bees or other pollinators have better odds of bringing pollen directly from one tree to another. But what if something less obvious and visible than either of these theories helped explain this phenomenon? What if the force driving it was something much smaller than a squirrel, or even a bee?

Researchers in Canada published a paper this past February in Current Biology proposing a new hypothesis for the evolution of seed masting: disease. While acorns are being gobbled up from above by hungry squirrels, they are also being attacked from below, and within, by fungi, bacteria and other pathogens. Scientists have understood for a long time that these agents can kill large numbers of seeds, but their role in determining the timing of seed release has been largely ignored. But some scientists wondered whether masting trees could drop fewer seeds in some years to break cycles of disease, rather than just to overwhelm predators in high years.

“Look at what farmers do,” says Jonathan Davies, a botanist and forest conservation scientist at the University of British Columbia, and one of the authors of the recent paper. “They often let the fields lie fallow, and that clears the pests and pathogens. You remove the crop for two, three or four years. It clears pathogens and pests from that field, and you can plant again.”

The idea that disease could play an important role was born, as many ideas are, not in a formal lab but in a casual conversation. Davies was talking to plant community ecologist Janneke Hille Ris Lambers of ETH Zurich about how variable the seed production was on the trees she studied in Washington state. The concept of pathogens as a driver came up, and Davies assumed that someone would have looked at that possibility before. But when he searched for references in journal databases, he was surprised to find an empty results screen.

“There was literally nothing in the literature about it,” says Davies.

Collecting data to support a theory like this would take decades, because of the time scales that govern tree reproduction. But before the pathogen escape hypothesis could be tested in the field, a solid foundation would have to be built, to make sure it worked even in theory. To start that process, the paper’s other author, math professor Ailene MacPherson of Simon Fraser University, came in and did what mathematical biologists do: She built a model.

The basic units of ecological theory are models, simplified representations of natural relationships that are expressed using math. Ecological models can be extremely complex, accounting for multiple species, environmental conditions and other variables. Since they were starting from a clean slate in terms of past research on the subject, MacPherson chose to use mathematical models that were as simple as possible.

“The idea was not to build the most robust models ever,” says MacPherson about the paper’s math, which she sees as a starting point and hopefully a launchpad for other researchers. “Our models are very much focused on illustrating that there might be a reason to study this.”

The closest thing to a pathogen model for seed masting in the literature was a 1992 study that looked at parasites. The paper used a version of a standard predator-prey model, like the squirrel and acorn, with basically two moving parts: seed and parasite. To adapt it for the new hypothesis, MacPherson considered two different ways that pathogens can spread: direct and environmental. Direct transmission spreads from one host to another. Environmental transmission can involve another step, either an intermediate host or another sort of reservoir where a pathogen can live between infections. A classic example is the bacterium that causes plague, which can be carried by rodents and then transmitted to humans through fleas.

Whichever method the pathogen uses, direct or environmental, there are two kinds of hosts to consider in a model: the already infected, and the susceptible, or not yet infected. According to MacPherson’s models, seed masting creates many susceptible seeds at once. In slow seeding years, the number of susceptible seeds can be so low that it could starve the next epidemic of hosts, cutting it off before it begins.

Now that the first steps of the theory are in place, Davies and MacPherson hope that other researchers can take the next steps, using more complex models and testing the theory against data in the field. One scientist who might incorporate some aspects of the theory into her work is the ecologist whose conversation with Davies sparked the idea in the first place.

Hille Ris Lambers has been studying trees and their population dynamics in Mount Rainier National Park since 2007. That data set has only recently gotten long enough, 16 years and counting, to start looking at masting patterns and, potentially, their relationship with disease. She finds the recent paper a promising start.

“I thought it was really nicely written and convincing to me that, yes, this is something that we’ve ignored as a potential long-term driver of some of these dynamics,” she says.

Rather than unseating predator satiation or pollinator efficiency as a leading theory, pathogen escape may just add to a mixture of drivers that all work together to push plant species toward masting.

“The reality is, there’s probably no one explanation,” says Davies. “This is probably going to be part of the explanation when we put this puzzle together.”

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Ian Rose | READ MORE