Screws

The answers to what screws are, why we need them, and many more are provided for curious readers. Screws help change a turning motion into an up-and-down movement. Screws, nuts, and bolts help keep many items in our world together. Readers will gain a valuable understanding of these simple machines through accessible text and colorful photographs. A comprehensive glossary and eye-catching graphic organizer aid readers in their exploration of these important science concepts.