We do a lot of drawing with markers and crayons on fabric. I find that in a class of 19, not only is it easy and cute, but all kids have success. After some trial and error, I have come up with a step-by-step picture guide that I use with my class. I thought it might be helpful for you, too.
Step 1: Draw on paper with pencil. (This ensures that the child is happy with the drawing.)
Step 2: Trace pencil lines with black marker or pen. (We love Flair pens!)
Step 3: Put fabric over drawing. Tape to table. Trace black lines with fabric markers.
Step 4: Color in with crayons. Have teacher iron fabric to set crayons. (Sometimes we just color with fabric markers, it depends what we're doing.)
We have made stuffed animals, pot holders, coasters, and quilts using this method. The top picture is from a "friendship quilt" we just completed. I'll post about that soon!
Some tips: I always cut the white paper a little smaller than the fabric to make a seam allowance. This process cuts down on mistakes which results in wasted fabric. The kids love seeing their drawings transferred into fabric art!