This reminds me of something someone on here said a long time ago. She put the little child sitting on her lap (or is it IN her lap??) and taught her to place her hands in the right place to hold the fabric and avoid stitching her fingers. The adult operated the foot pedal. I think his is a good way to be sure that they are learning the safe way.
At the children's class at Martha Pullen Sewing School, boxes were used to place the presser foot for the children to reach.