I've done something like this with giants, and my other smaller boids. I've done a few classroom lectures for my brothers class with Burms, Ball Pythons, and an African Rock. The kids seemed to enjoy it. Basically just tell them about the snake, where they come from, what they eat in the wild versus captivity etc. Keep it entertaining and such though. You don't want to make it boring or seem like it drags on. If the snake is tractable and handleable, allow some hands on with it by allowing a few at a time to come up and hold the snake. This will keep interest up, and make it more of a fun type of education versus book type education which seems to be a little better...especially working with younger people. Don't allow everyone at once to come up and basically harass the animal though. This can lead the animal to freak out or hesitate and can lead to someone getting bit. Since you won't be using a Giant, I don't need to mention much about that Just keep an eye out on the animal as well. Even if you feel its a 'predictable' specimen, there's still a possibility it can react unpredictably and undesireably. I have had an instance where one of my Burms have freaked when a kid pulled its tail and I almost took a face shot. You need to watch for things like this when allowing an interaction between kids and animals. Educate them a little on the do's and dont's of handling a reptile. You don't want any of the kids to get bitten, or injured. Good luck with the whole classroom deal.