Keith McCarthy

As soon as food touches your tongue, it begins a long process of moving through different parts of your body. This book explains how the human body breaks down food to get nutrients and stay healthy.

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.

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.

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.

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.

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.

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.