David Casserly wrote:
There's also always the option of just asking them to play what they know,
whatever they know, so long as it's well-phrased, playable at about 110 bpm
(a little slow for a contra normally but not for a one-dance stand) and has
an AABB format.
You might also want to specify that the A and B each have 16 beats.
(Or 8 bars at two beats to the bar).
Jeff