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 science fair project idea explores how length affects the weight a bridge can hold.

This science fair project idea investigates how the height at which a pendulum is released affects the length of time it continues.

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.

Introduce your fourth grader to the concepts of solstices by observing the length of her shadow on the shortest day of the year, compared to other solstices.

This science fair project idea explores whether it is easier to balance on a narrow ledge or on a rope.

In this classic Ivory soap experiment, kids learn what happens to different types of soap in the microwave, and why!

Take to the air with science by experimenting with helicopter seeds right in your own backyard!

This science fair project idea investigates how color affects temperature.

Here's a fun math and science activity: help your child explore four different kinds of measurement, using their hand and a few simple household tools.

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!

Has your kid noticed how much bigger the moon looks when it's low in the sky? Here's an activity you can do to show them that it's just an optical illusion.

Pair a planetarium visit with this fun art project that mimics the look of far-off galaxies.

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

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!

In this experiment you observe and determine how well your cat uses his whiskers to navigate through a maze.

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

Science fair project which measures the shadow cast by a meter stick at various times in order to predict the circumference of the earth.

Bring the fun of gardening indoors! By stuffing a simple pair of pantyhose with a few grass seeds on top, your child can grow her very own plant pet.

This science fair project idea investigates how optical distances change the apparent size of an object as seen through a magnifying lens.

Using a toy race car kids create a visual model of the Doppler Effect.

We all know that the Moon has different phases, but it can be hard to figure out why. Try this activity to see how the Moon's phases really work.

This science fair project idea investigates the difference in reaction times between boys and girls.

Learn how to make a ping pong ball anemometerâa device used to measure wind speedâin this free science fair project idea.

This science fair project idea measures the growth of bread dough and finds out how long it takes for the dough to stop rising.

Find out whether soil amendments can improve soil conditions and help you grow a bigger beanstalk in this ecology experiment!

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.

Jazz up your patio or backyard with hip and quirky planters made from simple Mason jars.

How good are humans at sound localization? Kids can try this cool science fair project idea to see how good their friends are at judging sound direction.

Make a DIY golf putter and design your own golf putting course in this 2nd-3rd grade arts and crafts/game activity.