Echolocation is the ability to orient by transmitting sound and receiving echoes from objects in the environment. As a result of a Marco-Polo type activity and subsequent lesson, students learn basic concepts of echolocation. They use these concepts to understand how dolphins use echolocation to locate prey, escape predators, navigate their environment, such as avoiding gillnets set by commercial fishing vessels. Students will also learn that dolphin sounds are vibrations created by vocal organs, and that sound is a type of wave or signal that carries energy and information especially in the dolphin's case. Students will learn that a dolphin's sense of hearing is highly enhanced and better than that of human hearing. Students will also be introduced to the concept of bycatch. Students will learn what happens to animals caught through bycatch and why.