Sally M. Walker

Electricity powers lights, computers, and television sets. But have you seen how electric...

The sun, furnaces, and ovens all make heat. But have you ever watched matter expand when ...

The sun, lightbulbs, and flickering fires all bring light to our world. But have you ever...

You know that magnets hold pictures on a refrigerator. But have you ever found a magnet's...

Solids, liquids, and gases are the three states of matter. But have you ever made matter ...

People, animals, machines, and wind all make sounds. But have you ever seen how sound wav...

Fossils give us a window to the past. Water, sediments, and pressure work together over t...

Minerals are fascinating resources that have a variety of uses. A diamond is a mineral th...

Rocks can be made of many different minerals. By looking at rocks closely, we can tell wh...

Soil can be found almost everywhere on Earth. Sand is a soft soil that is found in desert...

BONUS FEATURE: Enhanced CD featuring photos, maps, and illustrations from the book. For...

What do staircases, dump truck beds, and ramps have in common? All of them are inclined p...

What do hammers, wheelbarrows, and brooms have in common? All of them are levers! Levers ...

What do flagpoles and some window blinds have in common? They use pulleys to perform work...

What do jar tops and water-bottle lids have in common? Both of them are screws! Screws ar...

What do a doorstop, a butter knife, and the front of a boat have in common? All of them a...

What do bicycles, doorknobs, and screwdrivers have in common? All of them use wheels and ...