One of the key things kids learning elementary science is the basic groups of backboned animals. You may remember how to differentiate fish, birds, reptiles, amphibians, and mammals.

* Birds have feathers, lay eggs, and have bills.
* Reptiles are cold blooded, have scales, lay eggs, and some, like snakes, can inject venom.
* Amphibians are cold-blooded, lay eggs, breathe air but live on the land and in the water.
* Mammals are warm-blooded, have hair, give live births, and produce milk for their young

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