Art Teacher Hack: Line brick/cinder block walls with two rows of masking tape, and use hot glue to attach top corners of mounted art to the wall. Stays up as long as you need it to, and pops off easy when it's time to take it down.
Art teacher idea: classes earn a crayon for good behavior each day. They work towards crayons and when they earn them they can vote for a class celebration. Sidewalk Chalk Day, Art Video, Free Draw Day, Picture Book Art Day, or Color Explosion)