Had a geometry teacher once that drew the most incredible things on the black board...one day someone asked him how he go so good at drawing geometric shapes...he told us his secret...he drew them with objects before the class in pencil on the black board.
Teaching is retaining attention...had physics professor (physics for non-science majors, no math!!!) teaching us jocks...he could fold the university news paper under your arm with a piece of caulk from the front of the room! That got our attention!
I just swear.