These kinds of activities are good challenges to master during warm ups or gymnastics dance periods.  During each jump the legs straighten and the feet switch back and forth to end in the same position that the jump began.  After several repetitions the gymnasts change the feet position so they can practice the other side.  Some of the main goals are to maintain a vertical body position in the air and while landing on the ground  plus keeping the stomach in and the buttocks also tucked-in through the whole skill.