In this task, you're given a story (which contains five sentences only). Your task is to find all the characters which are available in the given story.

Sentence1: A boy in class found a rubber band on the floor. Sentence2: He stretched it across his fingers like a gun. Sentence3: The boy threatened his teacher with his rubber band. Sentence4: The teacher held her ground and did not flinch. Sentence5: The boy shot the teacher and the teacher caught it.
Boy, Teacher