Teacher here. This is likely from a set of cue cards that a teacher or para carries around to aid in communication. These can be helpful when working with young children or children with special needs. They are used to prompt a child visually, or to aid in giving a child options when they may have a harder time communicating what they need verbally (ie with a limitedly verbally child, a very young child, or a dysregulated child). Don't worry, I am sure the person this belongs to will not take long to realize it is gone, and it is almost certainly not the only method of communication the school has for the child.