A beaver's teeth never stop growing - just like a person's finger nails. Beavers prevent their teeth from growing back into their skulls by using them to gnaw on trees. Not only do they eat the leaves and inner bark of trees, but they also use trees as building material for their lodges and dams.
A dam is the structure built to create a pond. It is a stick and mud wall that holds the water. The dam creates a beaver "swimming pool" that serves as protection from predators.
A lodge is the beaver's home. It is like a castle with a protective moat around it. Inside the lodge, there is a room with special tunnels into the water.