After his parents divorced, Ryan lived with his mother. In this case, who was Ryan's custodial parent - his father or his mother?

Around the third week of a college class, a professor decides she’s had enough, is tired of dealing with bureaucracies, and wants out. so one day, instead of coming to class, she flies to tahiti and sells souvenirs on the beach. if this happened, the college would simply assign a substitute to finish the course. what does this tell you about the nature of the authority wielded by a professor?