Many of the things that you do every day may not seem like work, but in fact they are. For example if you walk, have a snack, or race around in the gym you are actually working. When a scientist talks about the definition of work, "they don't mean the opposite of play," but rather use it to mean "using force to move an object." When you pull or push something you are using force. If you put newspapers in your recycle box you are performing work, but if you push against a building you are not because the building doesn't move. You have to move an object from one place to another in order to call it work. Riding a bike would qualify as work. There are machines that can make your work easier. We have both complicated machines or simple ones. Complicated machines "have many moving parts, while simple have few. Would you believe that wheels on your computer chair are simple machines? They are.
Another thing you will explore in this book is friction, a force that makes a moving object slow down or stop." You will be able to experiment to find out how it works, learn how you can find it, and how you can lessen the effects of friction. If you take some of the same materials you used in the friction experiment (a spool and a straw), you'll learn about wheels and axles. You'll learn about different kids of wheels and axles, how and why the wheel travels a longer distance than the axle, which one takes more force to move by hand, you'll learn about gears, and you'll learn many other interesting things about wheels and axles at work. As you make your way through this book you will see other children work on experiments, experiments you too can conduct along with them.
This is an interesting book with which young students can experiment and learn about simple machines. There are several scientific concepts and information about simple machines that lead up to the discussion on wheels and axles. These include discussions about work, simple and complicated machines, friction, how they are defined and what they do. Each concept is accompanied by an experiment that is clearly defined by photographs of young students as they work through it. The book is generously illustrated with numerous photographs and a diagram displaying how gears work. I like the layout of the book and can easily see the benefits of using it in a homeschool or classroom setting. This is one in the series, "How Do Simple Machines Work?" In the back of the book is an index, a glossary, and additional recommended book and website resources to explore.