Why do police cars patrol the streets? Police cars help police officers fight crime and stop people from driving dangerously. Get a look into these cars and the equipment police use inside them.

Screws are simple machines used for many different jobs. The concept of a screw is used in snow blowers, drills, and presses. Kids will learn how screws work and how they are used in complex machines.

Have you ever seen a big truck on the highway? That is called a big rig. It transports many of the things we use in our everyday lives. Read about the different types of big rigs and how they transport cargo.

Pulleys are simple machines used to lift and move loads. Builders use pulley systems to lift tools or materials. Elevators use pulleys to move up and down. Kids will learn how pulleys make work easier and how they are often part of complex machines.

Ramps are simple machines used for work and play. Workers use them for easy loading and unloading. Skateboarders use them to do tricks. Readers will learn how ramps make work easier and how they are used in everyday life.

Gases, liquids, and solids are all matter. Everything that has mass and takes up space is matter. This book instructs eager learners about the different forms of matter and explains how matter can change forms.

Skid steer loaders are small construction machines that can do many different jobs. They are very useful for working in small places. Follow a skid steer loader as it drills a hole, lifts up a tree, or moves dirt.

Clear the road for the speeding ambulance! These vehicles need to get to an emergency as fast as possible. Learn about the equipment an ambulance carries and how ambulance workers save lives.

The planets in the solar system are in constant motion as they orbit the sun. Motion is all around! Children will get an introduction to the laws of motion and learn about speed, friction, and action and reaction.

Why is a small piece of metal heavier than a large piece of foam? Why does wood float in water? This books answers these questions as it teaches children about density in water and air.