There's a nice featurette on certain editions of A Bug's Life
and Sleeping Beauty
that illustrates what happens in a concise, understandable manner. For an even shorter demo, there's a picture inside the James Bond 007 Edition DVDs with the rectangle and square indicators. If those tools or a hand-drawn substitute don't work, then the matter may indeed be hopeless. The "smaller image = more picture information on a 4:3 TV set" concept is hard for many people, including my very intelligent mother, who also had to have the idea explained over the course of time.