Whenever I'm out teaching a class, or just on vacation with my kids, I always have them jump. Just like the old Toyota commercials (Its the "Oh what a feeling" tagline Toyota used for years in their commercials).
Everyone jumps differently... Its part of their personality. Some go high, some barely get off the ground. Others reach for the sky, and someone will invariably do a Ninja kick pretending to be Bruce Lee. I have done this with corporate executives, school kids and my family. They are always reluctant until you show them the results. Then they want to do more.
Here's the secret.... Get down low on the ground. Pick a fairly clean background. Sometimes putting your subjects on a little hill, with a sky behind can work, but most of the time, just find something fairly uncluttered. Now use a long lens ( I like to shoot at about 200mm lens distance) to drop out the background. Set your aperture fairly wide (perhaps f/4.0). Have your subjects do the counting, but be ready. Make sure your camera is set to continuous, or in sports mode. Ready, one, two, three JUMP. Fire away, and you should see personality floating in the air!
Special thanks to my energetic companions, Mark Alberhasky, Michael Paxton and Jamie T. Schander during an American Photo Mentor Trek in Kentucky, April 2008.