My father taught 5th grade and always had class pets. The children did much of the care, under his supervision, and it was overall a very positive and rewarding experience for everyone involved. Animals were only allowed out when a student finished their work for that segment - talk about incentive. I still get messages today, some 20 years later, from folks fondly remembering childhood encounters with the herps and inverts in my dad's class.

Being a high school teacher, your kids are going to have less leisure time as they shuffle from one class to the next. I doubt there will be much opportunity for interactions and caregiving for the students so a class pet will be more of an observational study and less an interactive one.

I suggest going with a local species if you don't mind expanding your collection. The students will learn how to identify at least one animal they might encounter outside of school, possibly saving a harmless species from being needlessly killed. I know around here "the only good snake is a dead snake" mentality was rampant until my pops came along.