In this project, you'll build a model of the earth, complete with all seven continents and four major oceans.

In this science fair project, young children will become aware of and have the opportunity to experience the four basic tastes: sweet, sour, salty, and bitter.

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.

Show your kids the power of baking powder by conducting a simple experiment. Make four batches of cornbread, all identical except for one thing: baking powder!

Here is a hands-on activity to help third graders understand the four points of a compass...and how we use them to get around.