An acquaintance has her 4 youngest kids with her (she has an older son who's living on his own). A 12-year-old, a 13-year-old, a 15-year-old, and a 17-year-old. For each A they get on their report cards they get $20 and for each B they get $10. Do you think money is a good reward for good grades? If yes, why? If not, what is a good reward? Do you think there should be a reward at all?