Barbara--As I'm certain you know, there's a very old tradition (at least where I grew up) called "strawing the fiddle," where one person takes heavy broomstraws and, standing facing the fiddler, hits the strings between the fiddler's left hand and the bow as the fiddler plays, providing a really nice percussive accompaniment. When my daughter and son were small, they would do this as I played my banjo; I felt, as you, that this gives them a nice sense of touch as well as a definite idea of beat and rhythm.