[header] How to do a knee flip on a trampoline [title] Allow your experience with front flips to act as a guide. [step] Before you jump, warm up by doing some stretches. Then start to bounce on the trampoline as you do when you attempt front flips. 
[substeps] Gain as much air as you can as you bounce on top of the trampoline. Repeat your jumps at least a handful of times to ensure you're getting the most air possible for your flip.