After Pine Needles I taught my then 7 yr old son the wedges in about ten minutes. I haven't said I thing about them since and he knows in the back of his brain that left is flat and right is bent. I'll stay pat with that for now.
I always get a lot out of your posts. I always just thought of the wedges to be common sense, no need for dowels or anything. But you're right it really does help to ingrain the hand positions into my ole' thick skull.