But always come back to basic pencil on paper. It's the skill and creativity, not exotic materials or tricks that really matter. While drawing from observation is not the only worthwhile learning task in art, it is very worthwhile for several reasons. Everybody wishes they could draw better. Drawing develops the right brain.
Drawing builds self-confidence.
Finally, drawing is one thing we do know how to teach. It gets us weaned from dependence on copying, which I still see in many of our schools. If first and second graders learn observation skills, they are less apt to have a crisis of confidence in the third grade when they begin to recognize the crudeness of their own work. The key to all teaching is to make it easy enough when they are beginners and hard enough when they become more skilled. Always keep them challenged, but never frustrated.