What would we look like without our bones? We'd be a sagging bag of skin. The bones in our body make up our skeletal system, which has many functions apart from the obvious one of providing a framework for the body. Bones, with the help of muscles and tendons (which connect muscle to bone) allow us to walk, write, play soccer, and breathe. Hinge and pivot joints, such as the elbow, connect the upper and lower arm, letting us arm wrestle. Ball and socket joints in the hip and shoulders make it possible to dance and do gymnastics. Beside the function of movement, bones protect our organs from injury and our brain from bumps. Bones are strong because the outside is made from calcium and other minerals, which are stored for the body's use. Inside bone is the spongy marrow that makes blood cells. A colorful x-ray photo illustrates the difference in bone growth of a three year old and an adult, and a striking photo of different types of bone accompanies a description of where each type is found in the body. A page on problems with bones describes the healing process when a bone breaks and, along with a skeletal illustration, the changes in the spine due to osteoporosis. A section on keeping bones healthy through diet and safety practices concludes with a photo of a smiling girl holding a large glass of milk. Each topic is explained on one page in easy-to-read print with a related photo on the page opposite. Significant words are highlighted and explained in a glossary and a few references are given for further study. This book is one of "Bridgestone Books Human Body Systems" series. It is an excellent introduction to body functions for early readers.