This book is very informative but also would have to include a lot of vocabulary lessons. For that reason I would use this book for older students. With younger students, I would read it out loud replacing the scientific vocabulary with words they understand. This book would be very useful in a lesson about marine mammals.

Some of the worlds best swimmers are not fish at all. They are mammals. The books talks about whales, dolphins, and mammals and the different facts about them and what makes them good swimmers