10 Is not too young. At 10 you are still very smart. If you wait till shes 18 you loose your intelligence as most teenagers think they know it all until they have their own kids. Plus at 18 they're invincible and don't have the fearful respect you can instill in a 10 year old. STRESS how extremely sharp the blade is over and over and let her see your worry. Tell her she can cut only as long as she cuts with you there and only if she cuts as you say. Next make sure she has a brand new blade to make cutting easier because as you know more force is applied with a more dull blade which is what could cause an accident. (Learned that at work and it is true!!!)