Stand beside the edge of the pool. Step on the noodle with your far leg (far from the edge). Hold the edge with straight arm. Keep your back straight and your far leg slightly in front of your body.
First bend your knee. This is easy because noodle is pushing your foot toward the surface. Second, push the noodle down. Here you will work against noodle's resistance.
Inhale when you bend. Exhale when you push down.
Feel your Quadriceps as you push the noodle down.