Chalk, my students of all ages love to use chalk. I have done several projects using just regular paper chalk, side walk chalk and the better quality chalk pastel. They love the ability to blend and swirl. One of the favorites of my students is freestyle art. They get to choose the art material they want to use and sometimes I give a broad topic other times I just leave them create. Chalk is one picked most often. Beautiful skies, flowers, space scenes have been created.