Don't use the corridor method of training.
ie Ok Bloggs I want you to run down that corridor as fast as you can and when you get to the end turn right and keep running.
So Bloggs goes running down the corridor and when he turns right impales himself on a brick wall.
Instructor says "Well, you won't do that again, will you?"
If the trainee asks you a question and you don't know the answer say "I don't know but lets go and find out"