Describe all visible parts of a face on a flipchart. Almost always the raised ridge leading from under the tip
of our nose to the top of the upper lip is left out! Try it out. Why do we do that? It is a part that we see everyday, yet we quite don't quite "see it". Also, nice to illustrate that the whole is bigger than the sum of its parts.
Do you have retreat tip you would like to share here? Drop me a line.