As a former school teacher and preschool director, please ask the art teacher first. I know folks have big hearts and want to donate to schools and most of the time these donations are much appreciated but ask if the teacher can use your scrap donation. If they cannot use it the donation will end up in the trash or stuffed in a cupboard for years and that is not what you want.
You may ask around your area or local quilt guilds too if any one can use your wee bitty scraps. I know we have someone who makes dog bed outs of scraps of batting. Never even considered that until she mentioned it in class one evening. There may be a secret user of small scraps just an arm length away.