I use green, yellow and red paint sample cards for this very purpose.
You usually can go to any Home Depot, etc. and get enough samples for an
entire class. Punch holes in them and use a binder ring to keep them
Green means they are working and need no assistance.
Yellow means they have a question but can continue to work.
Red means they cannot go any further without assistance.
It works out well. I suggest using Velcro, hooks, or library pockets to
keep them on the tables and in decent shape.
Art Teacher/ Beginning Teacher Mentor
Whitmore Charter School of the Arts and Technology
3435 Don Pedro Road
Ceres, CA 95307