A War of Gifts: An Ender Story Orson Scott Card

A War of Gifts, a short novel set during Ender Wiggin's first years at the Battle School where it is forbidden to celebrate religious holidays. The children come from many nations, many religions; while they are being trained for war, religious conflict between them is not on the curriculum. But Dink Meeker, one of the older students, doesn't see it that way. He thinks that giving gifts isn't exactly a religious observation, and on Sinterklaas Day he tucks a present into another student's shoe.