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!

Does the temperature of a magnet affect its strength? Learn about the relationship between magnets and temperature with this cool physics science fair project.

This science fair project on testing water hardness is a great introduction to practical chemistry. Test and learn the difference between hard and soft water.

What's the best way to make DIY compost? Kids will learn about aerobic and anaerobic decomposition while learning to appreciate the value of composting.

In this free science fair project idea, we learn about surface tension and how it can support mass—in this case, a floating paper clip.

In this simple science project, learn about what causes dew and what affects dew formation with a drinking glass, ice, and a soda bottle.

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 project, build an insect model that shows how the head, thorax, and abdomen fit together! Learn insect anatomy by constructing a paper mache critter.

This is a fantastic and easy science experiment where kids will learn about elasticity by testing how high bouncy balls of different materials can bounce.

In this plastic wrap science fair project, you'll learn about polymer permeability and find out which plastic wrap keeps food from dehydrating best.

Kids will learn how to make a thermometer to to explore liquid density in this great science fair project. Which liquids are affected by temperature the most?

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

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

In this experiment, kids will see if pruning tomato plants makes them more fruitful and learn about the factors that contribute to a plant's fruit production.

Kids will conduct a cool limewater carbon dioxide test that can be performed with common household materials to learn about the chemistry of this common gas.

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 do animals keep warm? In this experiment, find out whether fat insulation resists cold temperatures and learn how this works in the animal kingdom.

Here is a fun middle school science project on factors affecting solubility. Learn how dissolved solids can "crash out" to form crystals when conditions change.

In this science fair project, you'll make a "ghost" appear in a test tube, and learn about what happens when hot water and cold water interact.

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 are buttress roots? In this fun science project, make a model of a rainforest tree and learn how they help trees survive in the tropical rainforest!

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.

Kids build a desert food chain, desert food web, and desert food pyramid in this cool science fair project to learn about trophic levels and consumers.

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 fun science fair project idea learn about universal solvents and solutes and find out the solubility of several common liquid substances.

It's not actually that hard to get energy from garbage! Kids learn how to make biogas in the form of methane with this cool and easy science fair project idea.

In this project, learn about animal vision and different kinds of eyes: ocelli, compound eyes, and camera eyes. Find out what a jellyfish or grasshopper sees!

In this design thinking activity, your child will choose an animal to research, learn about the animal’s habitat, and then replicate the animal's habitat using household items.

Kids will learn how to make a steam powered rocket boat, also called a putt putt boat or a pop pop boat, in this great science fair project for 4th graders.