history: I interned for a Physical Education class for 3rd graders. I was stunned by how intelligent 3rd graders are!
current: I interned for a Physical Education class for third graders. I haven't been a third grader for a long time, so I was surprised how intelligent they are! They go through a lot of stuff, too.
next: That sounds awesome.  I barely remember 3rd grade.  I think we just played games and had fun.