But fortunately for most of us, the immune system is constantly on duty to battle germs that could make us ill. The following discussion questions and activities will help your students learn about how the immune system protects them from germs and illness.
Elephants however, go through six sets of 9lb teeth during their lifetimes, with new teeth growing in to replace old ones that have worn out. An elephants starts with two front teeth that fall out after about a year and are replaced by a set of tusks.
The number of teeth dinosaurs had varied dramatically, depending on the type of dinosaur. Some dinosaurs, like Ornithomimus and Gallimimus, did not have teeth. On the other end of the spectrum, Tyrannosaurus rex had 50 to 60 solid cone-shaped teeth as big as bananas. Hadrosaurs, or duck-billed dinosaurs, had the most teeth: up to 960 cheek teeth! Dinosaur teeth were replaceable. If a dinosaur broke or lost a tooth, another grew in to take the place, behaving much like sharks teeth do today.