I think it's cruel and disrespectful to assign vile math problems to children. Very disrespectful. I don't know if I could control myself if I were one of the parents. I always expected my children be treated with dignity by their teachers.
One of the problems was about cooking Americans and Africans in an oven. That isn't funny. Imagine an 8 year old picturing people in an oven. How dare a teacher bring that kind of imagery to his charges?
But we don't know which problems were actually assigned, do we?