More questions from our first grade class:

Why do frogs hop? 

Thanks, 
1C

Why frogs hop and don't walk or run is one of the biggest questions in the study of amphibian evolution, and different experts have proposed different answers.

It seems that hopping is the most sensible form of locomotion given the very short-bodied, tailless shape of modern frogs, but this is a bit of a chicken-and-egg situation because this body shape seems specialised for hopping. Modern frogs have very long legs, strongly modified hip bones and very short bodies that enable them to be expert leapers. The earliest fossil frogs had rather longer bodies and shorter legs and may have been good walkers, but for reasons we don't quite understand, the leaping specialisations came to be more important. Hopping may have been favoured as a good emergency defence tactic used when escaping from predators.

It is interesting to note that toads are the same basic shape as frogs yet they walk (some don't hop at all).

Jumping certainly appears to be a good escape response, perhaps someone should do a study investigating jumping responses and toxicity in Anurans - if you're poisonous you shouldn't need to jump to avoid predation...