If you have two or three people from each generation, that would give him a choice of interesting characters. His life and his value?
Yes, I think they sent the wrong homework home.
You are giving him a lot of encouragement for this homework. What happens to the children whose parents are not interested in helping? Do they get disheartened, and/or discouraged by the complexity of the subject? Then do they give up and get reprimanded for not submitting their homework? Call me old-fashioned, but I would think it is counter-productive to make it too difficult for the majority of children. The brighter/more motivated children could make it as detailed as they like.
I have a family tree somewhere that one of my Aunts researched, but it does not tell me about those people's lives. It could be difficult to find out very much about my Russian great grandfather, except that he travelled round the world extensively.
By the way, do you know what is meant by cousin once removed, twice removed etc?