I teach at a pre-school and I'm pretty sure the girl who cries acid tears when she doesn't get more clay than everyone else is one of our students. I say this without malice - in her four-year-old thinking, fair is when she does whatever she wants, and being asked to share is completely unreasonable. This is why she has teachers, family, etc to help her learn. Fortunately, we are all pretty immune to acid tears.