but over the past few months he has been coming home with more and more homework. ... He knows the material
I agree that relationship with the teacher is key. Do whatever you can to set up a time to sit down and see what her main concerns are.
I would - personally - not be willing to make a 2nd grader spend more than 10 minutes on work that he doesn't need in order to know the material 'cold.' I think 40 minutes is about the maximum I would allow under any circumstances. So look at the homework and see for yourself if you think it's needed. Most teachers are willing to accept it if you say, we did as much as I thought was appropriate, and I didn't allow him to do the rest. The fancy word for this is 'curriculum compacting.' Basically, that some kids need more practice to learn, and some need less, and the ones that need less - need less.
When my DS16 was this age, I would have been worried about 'If I don't make him do this meaningless homework, how will he ever be able to learn the habit of doing homework?' Since I believe that homework habit is important, knowing what I know now, I would substitute my own, deeper, broader homework. Then see if you can get agreement for your son to hand in his homework to the teacher. If no, just keep it yourself, and give your own report card. No one is going to care if he gets Bs in 2nd grade - and lowering his grade is the worst she can do.
I know a mom who sent her own worksheet in for her daughter to do during the school day. Yeah, she got the teacher's agreement on the first day of school.
If you act like you are comfortable with what you are doing (even if it's an act) most folks will take the path of least resistance and go with it.
Good luck,
Grinity
