The world is filled with objects made out of different materials, such as wood, glass, metal, plastic, and stone. Some materials are hard and some are soft. Some float and some sink. You can even see right through a few of them. Look inside to find out how materials are alike and different, the places they come from, and the many ways we use them every day.

We need light and sound to see and hear all the things around us. Without them, the world would be dark and quiet. Look inside to find out how light and sound move, how shadows and sounds are made, and many more fascinating facts about these very different kinds of energy.

Will you move faster going up or down a hill? Is it harder to slide down a snowy or a grassy slope? Force and motion play an important part in everyday life. Look inside to learn more about the way you move and what can make things go faster or slower.

We use electricity every day. Computers, telephones, and refrigerators all need it to work. With the flip of a switch, electricity lights homes, schools, and office buildings. What Is electricity, and where does it come from? How does it get to your home? Look Inside to find out more about this amazing form of energy.