A Class Pet???

I began toying with the idea of a class pet this weekend...I saw free turtles on craigslist and thought "those would be fun"--SO I got the ok from my principal but by then the turtles were gone.  However, I am not giving up on the class pet idea.  I have a new thought "what about a little lizard?"  I'm usually more of a furry animal lover but our district and principal worry about allergies with the furry babies! Does anyone have any thoughts on adopting a lizard for a classroom pet?  Am I getting myself into something difficult?  I'm sure the kids would LOVE a lizard but I'm more concerned with the start up and if it's a good choice.