How to get a natural smile from kids?

What are your tricks to get kids to smile quickly? This will be for dance classes, both group and individuals. They need to keep in a proper dance pose at the same time they smile, and with only a few seconds per photograph. Do you have any tricks? I would appreciate the assistance.....last year I often asked what ice cream they liked, while made them smile, they became animated and "lost" the pose.

Keep them relaxed and generally happy. Try to think out and set up the group shots as much as possible before getting the kids into position. Bring a rabbit's foot?

This may sound dumb, but it sometimes works in a pinch with younger kids. Have them say "hi" instead of "cheese" - usually results in a more natural smile! (Just make sure you snap at the very end of the "hi" or you'll have a wide open mouth!)