Most of us think of it as classroom supplies, but the $250 can also include "professional development courses related to the curriculum in which the educator provides instruction or to the students for which the educator provides instruction."  Apparently such courses can be paid from a Section 529 plan.  But there should be a way to show that the deduction relates to classroom supplies and not qualifying tuition.  Maybe it's called "override," but maybe the e-file police won't allow it.