Interesting facts about amphibians to tell kids include that they appeared earlier on the evolutionary ladder than reptiles, and there about 6,000 species worldwide. They were the first vertebrates to have four limbs, although an unusual type of amphibian, the caecilian, is limbless.
Amphibians haven't completely freed themselves from a watery environment. This means that most amphibians must have access to an area that's at least moist. One reason for this is because the eggs of most amphibians don't have hard shells, and need a watery medium to support them. Unlike reptiles, amphibians do not have scaly skin or claws on their feet. The skin of many amphibians is slimy, and some are able to breathe through their skin.
Amphibians also go through metamorphosis. Unlike reptiles, which are born looking like miniature versions of their parents, most amphibians are born looking nothing like their parents. Most toads and frogs begin life as tadpoles. They look like miniature fish because they have tails and gills. Eventually, their lungs develop, their limbs start to emerge, their tails shrink, and they are able to leave the water.
The largest amphibian in the world is the Chinese giant salamander, which can grow to 6 feet long. Among the smallest amphibians are the frogs Paedophryne dekot and Paedophryne verrucosa, found in Papua New Guinea. They're about 0.4 of an inch long.