Learn how to make a hygrometer to measure relative humidity in this project. Make a sling psychrometer hygrometer with gauze, thermometers, and a bottle.

Would it hurt to skip brushing your teeth just this once? Let's find out by seeing which foods produce the most mouth bacteria.

This science fair project idea explores whether cats can be trained in the same way that dogs can.

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

This science fair project idea explores alcoholic fermentation at work by making your own soda.

Demonstrate how you can make your own compass using a magnetized needle. It also allows you to compare magnetic north and geographic north.

Science fair project which tests various sedimentary, igneous and metamorphic rocks to find out whether one rock family is stronger than the others.

In this cool project, create a lighted, scale model of the different layers of the Sun, including the core, radiation and convection zones, and photosphere.

In this science fair projects, students will grow out the bacteria that collect on air conditioner filters.

Science fair project that identifies the differences between soils from different environments and attempts to figure out why those differences exist.

In this science fair project, students examine under what conditions individual plants release seeds and how far the seeds are released.

Kids will discover the meat science behind the meat they eat, and find out how to use safe chemistry to make meat more tender.

With this science fair idea, little scientists will gain valuable insights into the physics behind throwing a baseball.

This science fair project examines which fruits and/or vegetables will ripen prematurely when placed with ripe apples.

Soil is made up of different layers. How far down do you need to dig to find the soil horizon, or the place where bits of leaves and branches become soil?

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.

In this science fair project, students make their own rain gauge to measure rainfall.

This fun science fair project idea helps students learn how acid rains are formed and explore how acid rain damages the environment.

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 that examines how winter storms form and the relationship between temperature, moisture and snow.

Science fair project that determines whether landscaping fabric impacts the ability of plants to receive water.

This science fair project idea determines if crystals will absorb food dye and if colors will mix by the process of diffusion.

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.

What heats up fasterâwater or soil? 5th grade students test the specific heat of water against the specific heat of sand in this great science fair project.

What is condensation? Little mad scientists will learn about condensation, states of matter, and air pressure by conducting this cool science experiment.

In this fun science project, learn about what happens to cut fruit and experiment with how to stop apples from turning brown.

Why do ants like sugar? Do ants like artificial sweeteners too? Kids find out with this great inquiry-based science fair project.

This science fair project compares the allelopathic affects of juglone, a chemical agent produced by the Black Walnut tree, on two plants.

This science fair project teaches you about what makes persimmons so tart and how astringency can be removed by studying the effect of tannins on fruit.

Students explore hot desert plant adaptations in this cool science fair project by observing how these organisms prevent excessive transpiration.