Personally, I would just have him read what he wants and do the report on that, and
send it in as if that were what he had been assigned. We did that with math worksheets when DS was in 2nd grade -- only a couple of weeks of that, and the teacher told us that she wasn't expecting him to do those worksheets that he brought home, it was just habit to give one to every kid.
This has been our M.O. on pretty much every open-ended, "student determined" assignment-- right from the start.
So this is how my DD wound up discussing Langston Hughes' poetry in 3rd grade... even though it was (technically) a selection for middle school GT, reading middle and high school books in 6th grade for reports... doing research at the local university library for a 10th grade world history research project, etc. etc.
We just pretend like we "misunderstood" the directions. Whoopsie. Stupid us.
