If I remember correctly there is a law in America that doen´t allow to ship any organisms that are able to reproduce.
So shipping ordinary workers is allowed but shipping colonies with queens isn´t.
So basicly the choice you have is depending on where you live.
What age will the pupils be in your class?
I could imagine that a Pogonomyrmex colony would be interesting but since they are quite venomous they might not be accepted in the school.
You probably should contact the American forum: Hyperlinks sind nur für registrierte Nutzer sichtbar