Day 1 - S asked to bring a book to school, he typically doesn't ask to bring things so on the rare occassion when he does, we typically say yes. He wanted to bring a Thomas the Train book that plays music and was excited to show all his friends. When I went to pick him up at the end of the day the book was in the teacher's office, and so we forgot to bring it home and didn't remember it until it was too late to go back.
Day 2 - We retrieved the book from the office and I learned why it was there (instead of in his cubby, which is essentially public access although there are rules). One day 1 the music was playing and kids started dancing. S did not want them to dance to his music and told them to stop dancing, they couldn't dance. The teacher explained that when you bring a toy that plays music that other kids can hear, they can choose to dance if they want. Since the book was already at school we left it there for the remainder of day 2.
End of Day 2 - I pick S up and the book is once again in the teacher's office. This time his teacher explained kids were dancing and he didn't want them to. The solution - S could turn away, he didn't have to watch them dance if he didn't want to. S then decided he no longer wanted to share the book and put it in his cubby. Some of the younger kids were not good at following "the rules" and kept trying to take it out of his cubby to hear the music again. S asked the teacher to put the book in the office, and we brought it home with us at the end of the day.
Day 3 - The book stayed at home and S didn't ask to bring it to school again.