I don’t know about the kids feeling burdened by helping disadvantaged children. My kid is in a situation where he is helping an ESL kid. I asked him if it bothered him. He said it didn’t. The third grade is going to be way too easy for him anyway. He can be a little selfish and I think it could be good for him in a “value added” sort of way. I tell him that I am proud of him for helping his classmate.