Hi Cbelle!! I teach Urban Rebounding so I'll go ahead and give you a brief description. It's basically a workout done on a minitrampoline. However, these rebounders that are used are much more plyable than regular minitrampolines. They have more give. You work your legs very well on this because you don't go for height while jumping. In fact, you assume a squat position and push down into the rebounder and you shouldn't go any higher than about 6" in upward motion. You can do a varity of moves on it. Right now, I've included kickboxing/boxing moves into the workout. You work against gravity and G forces causing you to really need core strength and balance. It gets the heart rate up very quickly and keeps it there and is very easy on the joints my sis in law has had knee surgery and hasn't had a problem doing it. It's a definate calorie burner!! I have clocked my HR at 182bmp doing this, so I recommend getting down and taking a break whenever you feel you need one.
Well, I hope this helps answer some of your questions. If you take a class, let me know how you liked it!!
Aimee