Re: Metaphors for Teaching
Are these even really metaphors? Most of the examples in this thread seem like actual descriptions of physical movements. E.g. If you throw a pie on the ground you DO extend your arm and face your palm down, etc. If you want a student to put the back of their hand on their forehead, a picture of someone putting the back of their hand on their forehead is simply a description, isn't it? If something is actually an accurate description of a concrete body movement, what's wrong with that?
The one problem I can see is to make sure they realize that it's often just a first approximation. Once they get the basic idea further refinement will still be necessary and the refinement may no longer fully fit the earlier example.
What I think of as metaphors are things like when people talk about flowing water our your fingers or things that are more abstract and open to individual interpretation (and I find these far less useful).