In this science fair project, young children discover what happens when two fluids that have different densities get together.

In this experiment, students find out what happens when a less-dense fluid interacts with a denser one, replicating the effect of cooler solid rock on magma.

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

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

What is a wedge? Kids find out by experimenting with different wedges in this simple science fair project idea.

What causes dilated pupils? Young scientists will find out by applying what they already know about changes in pupil size and making models of the pupil.

This project examines what types of objects burn and which burn faster and cleaner.

What happens when colored beams of light mix? You might be surprised.

What is topography? Kids find out by learning to make and read a topographic map in this awesome science fair project idea.

What is mulch? Kids will provide soil with a wet blanket of mulch and see if that helps keep drought-stricken soil damp.

What is biodiversity? Kids will study different areas of their backyards to see which is the most diverse to learn about biodiversity and random sampling.

What is surface tension? Kids will discover how water-skating insects use surface tension to keep from sinking by making a model water walker.

In this experiment, your child will create two compost bins and see if he can determine what attracts fruit flies.

What is persistence of vision? With this hands-on science fair project idea, students will demonstrate this cool and dramatic phenomenon in their own classroom.

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

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

What do worms eat? Kids find out what kinds of rotting leaves and vegetables worms prefer in this cool compost science fair project.

What happens when eyes see something that the brain knows cannot be true? In this science activity, the brain has to "fudge" it when interpreting what you see.

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

What is elasticity? Students will investigate how this concept applies to bouncing ball physics by testing the bounces of balls made out of different materials.

Certain fruits can change gelatinâs ability to set. In this experiment, kids will discover what happens when gelatin meets pineapple enzyme.

Be a chemist for a day and study the simple reaction between sugar and heat. Try heating sugar and see what happens!

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 makes your shadow dance around all day? Let's play detective and find out why that sneaky shadow never stays in one place for long.

Try this activity with your child to explore what happens to rain (and the living things that need it) when it becomes polluted.

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.

Observe with your third grader what happens when food starts to decompose, and boost science skills simultaneously with this experiment!

Amaze your kids by separating a salt and pepper mixture using an "electric spoon" charged with wool.

Kids will learn some cool stuff about chemical reactions by determining what happens when you mix different concentrations of hydrogen peroxide and yeast.

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