Three main things make frogs good at telling us if an environment is sick. Find out what they are by answering 3 questions. It's easy.
Click on a question.
You'll see three pictures, one is the answer to the question. If you click on the right picture, you'll find out one of the cool, "different" things about frogs. If you click on the wrong one, try again.
Do this for all three questions and you'll discover why frogs are good at telling us if the environment is healthy.