Snake Skin
Bring in a snake skin and let your children examine them with a magnyfing glass.
Turtle Aquarium
Put an Aquarium in your room with a turtle in it. Ask your local pet store how
to set up the appropriate habitat. Children love to watch the turtle swim and
crawl around. Hint: Don't let your children touch the turtle (they can carry
diseases) 
Snake Matching
Talk about how different snakes have different patterns, color several snakes with different patterns (having at least two of every pattern) and let your children match them. 
One Hard Bite
Talk to your children aobut how hard an alligator can bite down. They will be
amazed at the force that the mouth can create. 
Frog Sequencing
Bring in cards that have the stages of a frog life cycle and have your children sequence them