I try to keep my lessons flexible enough that most typical art supplies can be used. Basic needs are a creating surface, something to make marks with, and something to add color. An eraser is an optional supply.
Creating-surfaces (this can be anything like paper, canvas, cardboard, your dirty socks ... maybe not your dirty socks)
Mark maker (pencil or pen or marker or charcoal)
Color adder (wax crayons, colored pencils, pencil crayons, color markers, paint - careful! some of these are messier than others so choose what is best for you)