What are some ways scientists classify amphibians and reptiles?

                                    http://www.sciencekids.co.nz/images/pictures/animals/snake.jpg
                                   
 I learned that frogs have skin that is smooth and slimy.  They are cold blooded and are vertebrates.  That means they have a backbone just like me.

http://www.sciencekids.co.nz/images/pictures/animals/snake.jpg

Did you know that snakes smell with their tongue? Snakes are covered in scales.  Snakeskin is smooth and dry. They are reptiles.

Standard 2.L.5A.1   How can you classify animals?