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 interdisciplinary card game will have your third grader working on math facts as he travels through the solar system!

Make your own marshmallows and mix up some very interesting third grade chemistry lessons while you're at it!

Crystals are a very special structure. In this third grade activity, your child will learn how to grow salt crystals.

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

Observe with your third grader what happens when food starts to decompose, and boost science skills simultaneously with this experiment!

If your science savy third grader is up for a challenge, let her bend light with a casserole dish!

Here is a hands-on activity to help third graders understand the four points of a compass...and how we use them to get around.

Your third grader will be amazed at the explosive combination of vinegar and baking soda in these chocolate volcano cupcakes with white chocolate "lava."

Learn about different fern fronds with your third grader as you create lacy, natural decorations on your Easter eggs this year.

Help your curious third grader construct a dazzling spinning wheel that will teach him about the science behind colors while providing some silly entertainment!

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.

Is it solid or liquid? Create oobleck and witness the amazingly weird oscillation between the two!

Encourage a group of third graders to play this fun game of Whistle Hide-and-Seek as a warm-up to get them prepared for finding a "lost" camper.

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.

This craft is a great way to explore the fascinating world of spiders and their webs as you collect spider webs from around your house with your third grader.

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

Your third grader will delight in learning about sound waves as he observes the different sounds created by tapping on glasses with varying amounts of water.

Want to spark your third grader's interest in gardening? Help him make popsicle stick fairies to decorate an enchanting garden oasis.

Invite your third grader to do taste test science to observe how a strawberry tastes when it is paired with various condiments. The results may be surprising!

Bring a little science to your third grader's Christmas as you test out his sense of smell by exposing him to common Christmas scents found in your kitchen.

Show your fifth grade scientist how to create a siphon using two buckets, plastic tubing, and water. Watch her astonishment as the water travels uphill!

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!

In this Halloween-themed activity, young learners will find out what happens when they mix two household items together to create a surprising chemical reaction.

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.