Stand by the edge of the pool. Step on the noodle with your far foot. Hold the edge with straight arm. Keep your back straight and your far leg slightly in front of your body.
Raise your far leg up toward the surface. This is easy because the noodle is pushing your foot toward the surface. Then pull the noodle down. It is very important to keep your leg straight. Here you will work against noodle's resistance. Make sure to pull down as deep as you can until the noodle touches the floor.
Inhale as you raise your leg up. Exhale as you pull down.
Feel your hamstring muscle as you pull the noodle down.