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.

Muscles help us lift, push, pull, and move. Eager readers will explore the different kinds of muscles, how their muscles work, and how to take care of them.

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.

We use wheels and axles several times every day. Young readers will learn how a wheel and axle work together, how they make work easier, and how they are used in larger, complex machines.

Movements called vibrations produce sound. Small vibrations make a quiet sound. Big vibrations make a loud sound. This book teaches children what sound is and how it can be measured.

How do we breathe and why do we need oxygen? Your lungs work hard to keep oxygen flowing through your blood. This book explains how the respiratory system functions to take in the air we need to live.

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.

Wave down a taxi and catch a ride! These helpful cars take people where they need to go. Beginning readers will learn how to catch a taxi, how taxis work, and where taxis can take people.

Winter winds blow snow at 35 miles per hour or more for at least three hours during a blizzard! Young readers will learn how blizzards form and why blizzard conditions temporarily shut down communities.

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.

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.

How does blood move around inside the human body? Students will learn all about the heart, blood cells, blood vessels, and other important parts of the circulatory system.