For this science fair project, kids will learn how to make a lemon battery. They can conduct this classic experiment using readily available materials.

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

How does dishwashing liquid work? Kids discover the chemical mechanism behind cleansing power in this easy science fair project idea.

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

How does a flashlight work? Kids will make a complete circuit and explore how voltage contributes to brightness with this science fair project idea.

In this cool science fair project idea, kids conduct the ruler drop test on volunteers to determine whether reaction time can be improved with practice.

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.

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.

This science project uses Mohsâ Hardness Test to show kids how to compare the hardness of different types of minerals.

Kids explore how a single movable pulley can confer a mechanical advantage over a fixed pulley in this cool engineering science fair project for 2nd grade.

What are the effects of fertilizer on plant growth? What's the best fertilizer type (solid, liquid or powder)? Kids find out in this science fair project idea.

Is it magic? No...it's the amazing, gravity-defying capillary action experiment! Kids will love this dramatic and enlightening science fair project.

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

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 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 will learn how to show the direction of magnetic field lines and create a permanent model using iron filings in this great science fair project idea.

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.

How does a compass work? What's a magnetic field? Kids will build their own compass at home to find the answers in this great science fair project idea.

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.

How does distance affect the spreading of light? Kids see diffraction and the inverse square law of light in action with this great science fair project idea.

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

In this free science fair project, learn how to separate salt from water using heat. A great science project for elementary school kids.

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 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.

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 science fair project, kids observe the expansion of liquids when frozen and determine if some liquids expand more than others in the freezing process.

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.

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.

Do hand soaps and sanitizers prevent the growth of bread mold? If so, why? Kids will find out with this fun and informative science fair project idea.