Actually I kinda like the idea of giving Susan private lessons...

A tape recording might prove quite valuable. Maybe you and Glenn could have a short session with her and have her play the way she always does. Tape it. Play it back and try to help her hear the problem areas. If she just can't hear it, then the sand egg sounds like the place to go.

BTW, I didn't mean to sound as hard as I did in my previous post. There was a little girl at Anna's gathering who was having a great time playing a washboard I had brought. She wasn't anywhere near to being with the beat and was sometimes playing during tunes or songs which may not have been appropriate vehicles for such accompaniment. But she was really trying to play. And she wasn't especially obtrusive. I would never want to discourage that kind of enthusiasm. I would want to encourage Susan to find an avenue of musical expression. Maybe a rhythm instrument just isn't her thing. Maybe she could try an autoharp. (Not that you don't have to have a sense of rhythm to play virtually anything; but some are more flexible than others IMHO.)