40 Easy Science Fair Ideas for Elementary Students

The best elementary science fair ideas are simple, safe and easy to measure: your child changes one thing, keeps everything else the same and records what happens. Below are 40 easy ideas grouped by topic, each written as a testable question with a hint about what to measure. Pick a few that match your child's interests and let them choose the winner.

How to Pick the Right Idea

Before scrolling the list, keep three filters in mind. First, your child should be genuinely curious about the question, because interest carries them through the boring parts. Second, the test should finish in a week or two, so there is time to repeat trials and build the board. Third, the supplies should already be at home or cost very little.

Every idea below is a real experiment, not just a demonstration. That means there is one thing to change (the independent variable), one thing to measure (the dependent variable) and a plan to keep everything else the same. If your teacher allows younger kids to do a model or demonstration, you can still use these ideas and simply skip some of the measuring.

The 40 Ideas by Topic

Water, Ice and Liquids (Ideas 1–10)

1. Which melts ice fastest: salt, sugar or sand? Sprinkle each on identical ice cubes and time the melting.
2. Where in the house does ice melt fastest? Place cubes in different rooms and record the minutes.
3. Which paper towel absorbs the most water? Dip equal squares and measure the water squeezed out.
4. Does water temperature change how fast sugar dissolves? Use cool, room-temperature and warm tap water with an adult.
5. Which liquid evaporates fastest? Leave equal amounts of water, salt water and juice in shallow dishes and measure what remains each day.
6. Do celery stalks drink colored water faster in warm or cool water? Measure how high the color climbs after a set time.
7. Does salt help an egg float? Add salt one spoonful at a time and record when the egg rises.
8. Which cup keeps water cold longest? Compare paper, plastic and foam cups with a kitchen thermometer.
9. Does the shape of an ice cube change melting time? Freeze water in different molds and time each one.
10. Which fabric dries fastest? Wet equal squares of cotton, polyester and wool, then check them every 15 minutes.

Plants and Seeds (Ideas 11–18)

11. Do bean seeds sprout faster in a damp paper towel or in soil? Count days to the first sprout.
12. Does the amount of light change how tall a plant grows? Compare a sunny window, a shady room and a closet for a few hours a day.
13. Does music help plants grow? Keep two groups of plants in identical conditions, play music near one and measure height weekly.
14. Which liquid helps seeds sprout best: tap water, rainwater or bottled water? Track sprouts and height.
15. Do seeds sprout faster if soaked overnight first? Compare soaked and unsoaked seeds.
16. Which way do roots grow if you turn the seed upside down? Use clear cups so roots are visible and draw them daily.
17. Does the size of the pot change plant growth? Plant identical seeds in small, medium and large containers.
18. Do plants grow toward light? Place a seedling in a shoebox with a hole in one side and photograph the bend each day.

Motion, Force and Simple Machines (Ideas 19–28)

19. Does the height of a ramp change how far a toy car rolls? Prop a board on books and measure distance.
20. Which surface lets a toy car roll farthest: carpet, tile or wood? Use the same ramp height each time.
21. Does the size of a parachute change how slowly it falls? Make plastic bag parachutes in three sizes and time the drop.
22. Which paper airplane design flies the farthest? Fly three designs three times each.
23. Does a ball bounce higher on grass, concrete or carpet? Drop from the same height and measure the bounce.
24. Does air pressure in a ball change how high it bounces? Compare a fully pumped ball and a softer one.
25. Which lever position lifts a load easiest? Use a ruler balanced on a pencil and count pennies needed to lift a small toy.
26. Does adding weight make a balloon car go farther or shorter? Tape coins to a simple car and measure distance.
27. Does the length of a pendulum change how fast it swings? Tie a washer to strings of different lengths and count swings in 30 seconds.
28. Which shape of paper column holds the most books? Fold paper into circles, triangles and squares and stack books carefully.

Light, Heat and Weather (Ideas 29–35)

29. Do darker colors heat up faster in the sun? Place colored paper over thermometers outside and record temperatures.
30. Which material blocks the most sunlight? Cover cups of water with foil, paper and fabric and compare temperatures.
31. Does the time of day change the length of your shadow? Measure a shadow at morning, noon and afternoon.
32. How much rain falls in a week? Build a simple rain gauge from a clear container and a ruler, and compare to cloudy versus sunny days.
33. Which way does the wind blow most often at your house? Make a paper wind vane and record direction daily.
34. Does a cup of water cool faster with a lid or without one? Start with warm tap water and use a thermometer, with adult help.
35. Which sunglasses block the most light? Shine a flashlight through different lenses onto paper and compare brightness with a simple scale.

Everyday Kitchen and Body Science (Ideas 36–40)

36. Which apple slice browns slowest: plain, lemon juice or salt water? Photograph slices every hour and compare.
37. Does bread grow mold faster in a dark cupboard or on the counter? Keep slices in sealed bags and never open them; an adult throws them away unopened.
38. Does your heart beat faster after jumping jacks? Count pulse for 15 seconds before and after short exercise.
39. Which hand is faster at catching a dropped ruler? Measure where fingers catch the ruler and compare both hands.
40. Can you taste the difference with your nose plugged? Have family members taste small pieces of apple and pear with eyes closed and nose pinched, and record correct guesses.

Parent tip: Print or copy this list and let your child circle five ideas that sound fun. Then cross off any that need supplies you do not have or will take too long. Choosing from a short list of their own favorites keeps kids excited without overwhelming them.

Making Any Idea Science Fair Ready

Once your child has picked an idea, help them turn it into a complete project:

1. Write the question at the top of a notebook page.
2. Research the topic in a library book or kid-friendly website and write two or three facts.
3. Write a hypothesis using "I think ___ because ___."
4. List what changes, what you measure and what stays the same.
5. Test at least three times for each group so results are fair.
6. Record results in a table and color a simple bar graph.
7. Write a conclusion explaining whether the hypothesis was supported.
8. Build a tri-fold board with the question on the left, the experiment in the middle and results on the right.

Keep every idea safe. Adults should handle anything warm, sharp, or involving hot glue or batteries. Avoid any project that uses flames, harsh chemicals or could stress or harm an animal. If your child is curious about something that needs special approval, such as testing on people or growing bacteria, ask the teacher and check your official rulebook first.

Quick Checklist

Tap the boxes as you go — progress saves on this device only.

• Circle five ideas you like
• Pick your favorite one
• Ask your teacher if it is okay
• Gather your supplies
• Write your question and your guess
• Test it three times
• Write down your results
• Make a bar graph
• Build your board
• Practice telling someone about it

Time and Cost Estimate

A simple question tested carefully is exactly what elementary judges hope to see. Pick an idea that makes your child smile, start early, and enjoy discovering the answer together.