I'm in the process being the "technical advisor" for my granddaughter's 1st grade class. They'll draw directly on the muslin squares with fabric markers.
I experimented, using masking tape to tape the cut square with border marked on to a piece of cardboard, worked great & granddaughter had control of her drawing because fabric not moving around.
I did the same thing a few years ago for another class, they loved it & came out so cute.