The trampoline was added in the recent outdoor update. With the trampoline you can jump up to 10 blocks high. It requires 3 blue wool, a string, and 4 stone. place the string in the middle top, blue wool on the top left and top right and exact middle, and then place the stone on the middle left and right and bottom left and right.
*Adding trampolines next to each other will join together to make a bigger trampoline.