is there a homework cheat?

Don't worry about doing homework every night for every kid. If each kid can get their homework done once or twice a week and occasionally go to school focused. Well before the the time they come to age up, they will be bragging about their grades.

In addition, if you are considering a cheat and really don't want to use one, then you can simply turn aging off for that household and you will have all the time in the world to get them those As, along with a pile of other skills :)