Get them familiar with dry firing, holding and mounting correctly indoors at home. Dry mounting on the ceiling cornices is good practice for all of us.
If you and your pupil are confident and familiar with gun mounting through daily dry practice your more than half way there. The gun has to be pointing where the shooter is looking when the stock hits the shoulder.
If they're keen /willing pupils they'll work at dry practice if the promised reward of live shooting is delayed a week or two.

Teaching kids to shoot is all about having fun. Shooting all afternoon and not hitting anything is not fun. If you can afford it I would recommend buying an inexpensive 20 gauge with interchangeable chokes to improve their chances. I would also start them with rolling targets like tires with ballons tied in the center to help get thier swing going. Most importantly keep the trainining sessions short and fun. GOOD LUCK.