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.

This science fair project idea explores whether a sundial is as accurate as an atomic clock when telling time.

How do the phases of the Moon and gravity cause spring tides and neap tides? Does the Sun play a role in the tides? Figure it out in this fun science project!

This science fair project creates a visual model of whatâs happening to sound waves as a car approaches and then leaves.

In this activity, your child will be challenged to use simple materials to create a catapult for a small, lightweight toy.

Learn about magnifying glasses, concave lenses and inverted images by sending rays of light through a magnifying glass in this cool science fair project!

In this fun design challenge, your child will get creative with making structures out of toothpicks and gumdrop candies.

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.

In this exciting and empowering challenge, your child will construct a bridge using marshmallows and toothpicks!

Magnets vary in strength. Have your young scientist figure out which kind of magnet is the strongest when you have him conduct this attractive experiment.

Create a DIY Electromagnet! Using a 9v battery to create an electrical field around a nail, students explore electromagnetism in this cool science project idea.

In this project, all you need is a protractor to learn how to use the altitude of Polaris to find latitude on Earth. Polaris is also known as the North Star.

In this free science fair project, build a star clock and learn how to tell time on a clear night by observing the big dipper!

In this activity, your child will be asked to create a boat that can successfully float while holding 25 pennies.

This science fair project idea investigates how color affects temperature.

This science fair project idea explores if the length of the string that an object is suspended on has an effect on how fast or slow it swings.

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

What causes the seasons to change? Kids find out by modeling the earth's tilt using a globe, flashlight and graph paper in this cool science fair project idea.

This science fair project idea investigates if heat from direct sunlight is hotter than heat from reflected sunlight.

Is it amplitude? Weight? Length of string? Kids will discover what factors changing the period of a pendulum depends on in this fun and easy physics experiment.

Kids will create their own version of Richard Feynman's rubber band heat engine to learn about thermodynamics with this cool science fair project idea.

Handedness and footedness refer to whether people prefer to use their left or right hand and foot. In this experiment, test hand and foot dominance.

In this science fair project, we'll use a liquid crystal thermometer to find out whether exercising makes a difference in people's temperature.

This classic children's game demonstrates how sound travels through air vs. through a solid.

This science fair project examines how seeds hitchhike on animals and clothing.

This science fair project teaches kids experimental design and how to test if subjects can really sense if they are being watched.

In this science experiment, do tensile strength test on fishing line, a strand of hair, a rubber band, and any other materials you're curious about!

Kids learn how to prevent erosion by growing grass. They'll test soil with grass against raw soil in this revealing science fair project idea for 4th grade.

In this science fair project, students create their own miniature salt flats at home.

This science fair project idea examines whether boys and girls differ in reflexes.