Science Fair Ideas for Third Graders

By Rachel Patel · October 7, 2026

What Makes a Good Third-Grade Project

At this age, projects should have one clear variable to change, one thing to measure, and at least three trials. The scientific method should be visible but not overwhelming.

Top Project Ideas

1. Which Paper Towel Brand Holds the Most Water?

Test three brands by soaking equal-sized pieces, then squeezing water into a measuring cup. Record results in a bar graph. Cost comparison adds a math angle.

2. Does Music Affect Plant Growth?

Grow three identical bean plants. One gets classical music, one gets rock, one gets silence. Measure height daily for two weeks. Controls: same soil, water, light.

3. What Temperature Makes Yeast Grow Fastest?

Mix yeast with sugar water at cold, room, and warm temperatures. Measure the balloon inflation on top of each bottle over one hour.

4. Which Surface Creates the Most Friction?

Roll a toy car down a ramp onto different surfaces: carpet, tile, sandpaper, foil. Measure distance traveled. Graph the results.

5. Does Color Affect Taste Perception?

Dye lemonade different colors (same recipe). Have blindfolded tasters rate sweetness. Does red taste sweeter than green?

Tips for a Winning Display

Use a tri-fold board with clear sections: Question, Hypothesis, Procedure, Data, Conclusion. Include photos of the experiment in progress. Let your child hand-write the text—judges know when parents did the work.