They are all the same size

In a country home that seldom had guests, a young son was eager to help his mother after his father appeared with two dinner guests.

When the dinner was nearly over, the boy went to the kitchen and proudly carried in the first piece of apple pie, giving it to his father, who passed it to a guest.

The boy came in with a second piece of pie and gave it to his father, who again gave it to a guest.

This was too much for the boy, who said, "It's no use, Dad. The pieces are all the same size."