If you have a 4th grader, who has a class (e.g. you are a parent), it is this:
W*hat sorts of things are being *taught* in my 4th *grader's class?
If you have a class, which is a 4th graders' class, (e.g. you are a 4th grader, or the teacher) it is this:
W*hat sorts of things are being *taught in my 4th *graders'* class?
The difference is the apos