Apples have a long history of greasing the wheels of education, the juicy fruit is a traditional present for teachers in the United States, Denmark, and Sweden. Some think the practice originated as a simple gift of food for poorly paid teachers. Others believe the good health associated with apples made the present particularly meaningful. And a few even think it's a nice name for a child.
When public schools were established, sending an apple to the teacher was a way for families to say thank you to the teacher, as well as a way for a student to "apple-polish", or to apologize for misbehaving, or to let the teacher know the student liked the teacher.
When education was first instituted, it was not free, there was sometimes a hefty fee to education. However, most families were poor country farmers. Since food and services were considered more valuable than money, these would be traded for the tuition. Some Private schools and colleges still do this today, but it is call the "Work Study" program today. This payment may come in bushels of fruit and grain, or a new roof, or a cord of wood, or fabric for clothing. Since it was rare to give the food all at once (it will spoil), the student would give an apple a day to ensure that the teacher would receive the full payment of food in fresh unspoiled produce.