We can use many different things to measure length. We decide on what unit to use by what object we are measuring. The unit sizes in formal measurement are the spaces between the lines, not the lines themselves. Head up and eyes looking forward. Arms extend behind body as legs bend.
Legs extend forcefully.
Jump is evenly off both feet. Arm action is strong and synchronized with leg action. Use arm swing to gain height or distance. Bend knees, ankles, and hips to absorb force on landing. On landing, lean forward slightly at the hips.