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

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!

In this cool science experiment, learn about magnetism and poles, and test magnet strength to find out if two magnets are twice as strong as one.

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

This science fair project compares the allelopathic affects of juglone, a chemical agent produced by the Black Walnut tree, on two plants.

In this science fair project, young children discover what happens when two fluids that have different densities get together.

In this popcorn experiment, students can explore how two things made out of the same material can have very different appearances and densities.

In this experiment, your child will create two compost bins and see if he can determine what attracts fruit flies.

Milk is made of water and fat; but how can you separate the two? Find out in this color changing milk experiment.

This classic children's game-connecting two cups with a string-demonstrates sound's ability to travel through air vs through a solid.

In this fun science fair project, make two different scale models of our solar system using Astronomical Units and planets' relative size!

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.

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

Do you love to make Jell-O? Find out in this science fair project idea if it is possible to make Jell-O with just warm water.

This science project teaches students the relationship between compost and plant growth. Students conduct an experiment with different types of compost.

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

In this microwave plant experiment, find out whether microwave radiation will affect radish seed germination. Will it help or hinder the plants' growth?

How would you dry your wet clothes if your dryer didn't work? Find out with this fun experiment!

Kids will learn about the interaction of lactose and lactase in milk and discover why we describe enzymes as catalysts in this fun science fair project.

Here's a great activity that uses corks and toothpicks to create a fleet of floating boats. Which design makes for the most seaworthy vessel?

These science fair experiments demonstrate the chemistry of rust and the oxidation process.

Find out whether putting something on top of a plant will inhibit its growth.

The objective of this science fair project is to analyze the effects of salinity and temperature on water.

How does rust form? Kids will learn about the roles oxygen, water, and electrons play in rust chemistry in this cool science fair project idea.

What cause the phases of the moon? Make a model to see how the positions of the Sun, Moon, and Earth cause the crescent, gibbous, quarter, full, and new moon.

The objective of this science fair project is to set up a compost bin to convert food scraps and organic waste.

This science fair project idea explores whether the process used to dry the beans we eat for food renders them unviable.

This science fair project idea discovers whether there are some objects that do not fall at a constant rate.

Want to see a great example of Newton's first law? Kids will learn about basic physics with this fun, ballistic experiment.