When I was a kid the best part of going back to school was getting all new art supplies: crayons, pencils, erasers, paper, and a set of Prang watercolors complete with brush. That was BC (before computers) when we had low-tech materials and used some pretty basic techniques. One day the teacher showed us how to make crayon rubbings. We ran around making rubbings of all kinds of things, but my favorite was finding and using leaves. From those humble beginnings, I developed an interest in making scientifically accurate plant drawings, so by the time I got to high school Biology class I had a corner on the market of plant illustration, and firmly believe it was what allowed me to actually pass the class.
Making rubbings is still a good way to introduce the appreciation of nature and science, and it can be used as part of educational outreach programs for both children and adults. As a one-time event, in which the rubbing becomes the end product, is particularly good for dealing with younger children who have much shorter attention spans and a need for hands-on activities.