Hi Sandy: As educators we've probably learned to use whatever we have as training aids. But if we have choices, the more varied and useful to convey the lesson message, the more beneficial the lesson will be. Breaking up or mixing up different media into segments helps keep a good attention span. Just as the mind begins to wander (about 20 minutes), swith to a different media. PPT, with whiteboard, with training aid, with written exercise, with textbook reading, back to PPT, etc. Incorporating lab will also help cement the practical aspects. Regards, Barry