This is critical. The worker must see it done properly. If the supervisor is not fully qualified, get another person. However, the supervisor should always be involved. At regular intervals, ask the worker if he or she understands the process or procedure.
Involvement Ask the worker to perform safe procedures.
Demonstration is at the very heart of the training. Never trivialize it. Your approach should reflect concern for their success. Their success is your success. Practice until you and workers are confident.