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!

What keeps a an item cooler, polymer crystals or ice? Find out in this cool science experiment!

This science fair project idea creates cool new colorful fabric pattern designs and experiments with the mixing of colors.

This science fair project idea researches how your choice of clothing affect how hot or cool you feel during the day.

How does salinity affect the point at which water freezes? Kids will find out by performing this cool melting ice experiment.

This cool science fair project teaches kids about temperature, density and buoyancy using balloons that float with normal air. No helium required!

In this fun science experiment, kids will determine the best method for ripening avocados and discover the cool chemical reaction that makes this possible.

Delight your budding scientist with this cool physics magic trick and teach her some basic physics concepts while you're at it!

Kids will learn some cool stuff about chemical reactions by determining what happens when you mix different concentrations of hydrogen peroxide and yeast.

What is a compound microscope? Kids find out by making one of their own in this cool science fair project.

How does water pressure change with depth? Kids learn how pressure works underwater with this cool and easy demo.

Check out this cool science fair project idea that models the behavior of the cold desert plants: xerophytes and halophytes.

What do ants eat? Kids find out by observing a colony of ants in this cool zoology science fair project for 4th grade.

What is persistence of vision? With this hands-on science fair project idea, students will demonstrate this cool and dramatic phenomenon in their own classroom.

Kids learn how to manipulate additive and subtractive colors to send secret messages with red colored filters in this cool science fair project idea.

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.

Kids construct a single fixed pulley system to learn how pulleys can make work easier in this cool physics and engineering science fair project idea.

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.

Check out this cool science project idea to learn about rocks and explore the cycles of formation, breakdown, and reformation of rocks in the Earth's crust.

Learn how to tell time by the sun with this cool science fair project idea that tracks how the accuracy of a sundial changes over time.

Think you can blow up a balloon without using your mouth? This isn't just a cool trick, it's also a great way to introduce chemistry and biology concepts.

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

Can a toy car determine the strength of a magnet? In this cool magnet science fair project, young scientists will learn how to measure the strength of a magnet.

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!

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.

Build a 3d animal cell model with this cool science fair project, which helps kids visualize and understand the function of a cell's parts and organelles.

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

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