How fun!!
Bring baby wipes, paper towels, and hand sanitizer if you're going to let the kids hold the birds. Nothing grosses my kids out faster than being pooped on. Usually the other kids look on and laugh until they're pooped on too. They now put a paper towel in their lap if they're sitting and holding a bird. The baby wipes and hand sanitizer are for the kids before and after they touch the birds.
I don't know how many birds you're brining in or how old the kids are, but, if you're in an urban area, chances are the kids have never touched a bird. The kids will probably be really excited. Ensure you have enough adult supervision so your birds don't get hurt. (My DD just reminded me a few days ago she'd never touched a bird until we got ours a month ago.)
Take in any pictures you have of the same birds over the last 3 weeks so the kids can see how things change. Heck, you might even remind the teacher to bring a digital camera or bring one of your own. It will be an exciting day for all!
I hate to even say it. CYA. Get a statement asking you to bring the birds in. Make sure their insurance covers you or get your own for this visit. You don't want your good deed turning bad because one of the kids gets 'bird flu' in the next few weeks or if one has an allergic reaction to birds. It doesn't matter what is true (ie your healthy birds didn't cause the issue). Parents are not always rational, and they can make your life hell in the process. Taking this one step further, heaven forbid, if a bird is injured or worse, are you prepared to deal with it and not blame the child? Will the school reimburse you for your vet expenses or a replacement? I'm sure nothing bad will happen, but I'm one of those prepare-for-the-worst people because you never seem to deal with the worst if you've prepared for it.