Did you know your body is full of simple machines? This project looks at one of the third-class levers in the human body: your arm!

Kids will enjoy this cool demonstration of Newton's Third Law and the conservation of linear momentum.

In this cool engineering science fair project, kids learn how to build Hero's engine: an enlightening example of Newton's third law.

Study the impact of environment on seed germination among three materials: soil, paper towel, and cloth. Note when seeds germinate and how well they germinate

This project examines whether humans can intuitively grasp numeric values greater than three.

Store seeds under three different environmental conditions. Plant seeds in carefully marked groups, watch them grow. Compare results.

This project compares the strength of one, two, and three-ply toilet paper.

In this investigation, three different juices are tested to determine which juice contains the greatest amount of vitamin C.

This science fair project idea examines the actual cost of three household light bulbs by testing energy consumption.

Examine which metal conducts more heat by boiling water in 3 pans made of aluminum, copper, and stainless steel.

In this cool project, create a lighted, scale model of the different layers of the Sun, including the core, radiation and convection zones, and photosphere.

This project explores how and how much one family can reduce the amount of garbage they accumulate over a three month period.

The project compares three different methods of testing turbidity in water: the secchi disk, spectrophotometer, and turbidity test kit.

Science fair project the demonstrates Newton's Third Law using a milk carton filled with water.

How do crystals form? In this science fair project, students will use three different saturated solutions to see how different minerals form crystals over time.

Test products which claim to reduce wrinkles, and determine which is the most effective. Test effectiveness over three weeks, using a sample of volunteers.

In this open-ended activity, students will be given a small quantity of three types of materials and asked to design a prototype for “something that will improve the school.”

Explore the craters, maria, and highlands on the surface of the Moon! In this fun science project you'll create a 3-D model of the moon using paper mache.

Check out this fun middle school science fair project idea on Newton's third law of motion and how you can change the speed of a rocket.

Check out this fun and easy 4th grade science fair project idea that tests how gravity induces positive and negative geotropism (gravitropism) in bean plants.

Experiment with buoyancy to learn how a submarine rises and sinks in this classic science experiment.

This experiment will determine how different kinds of light affects the strength of bakerâs yeast.

Alive or not? This yeast experiment you can conduct with your little scientist explores the answer to this timeless question.

The purpose of this science fair project is to demonstrate how yeast, a fungus, causes bread to rise.

Free science fair project idea examining how different types of water affect plant germination and growth.

This experiment explores how microwave radiation affects fungi, bacteria, and plant life.

Is it a square or a circle? See if you can trick your friends with this zany science project!

Science fair project that tests the effects of diluted soap on the size of bubbles blown from the solution. Will dilution cause smaller bubbles?