I know that there can be pets but I do not know the boundries of what is allowed or not. Fish great, hamster/gerbil, maybe a hermet crab or turtle, or grow butterflies and release... but beyound that I would not be comfortable with it because if it is not ina fully inclosed (like glass/plastic cage) then it is too easy for a child or even adult to stick their finger in.
Also I thought that any animal that someone could be allergic to it has to be OK'ed by EVERYONE (child/adult) that is in that room to make sure that they are not being harmed in any way. The animal also has to be up to date on vet checks as well as rehibilated (which a perfessonial has to do).
A bird usually is not the best because the do "bite" or peck and it can draw blood easily and with an "open" cage I would fight to make sure it was either in a office, NOT a CLASSROOM or out of the building all together. Birds can be nosiey and find the irrating and would NEVER want one to be in a classroom where kids are easily distracted because of the noise.