Movement:
Keep your head slightly elevated ( to push your lower back into the floor for lumbar support and also to increase tension on the abs). Keep your arms flat with palms facing down.
Raise your legs with a slight bend at the knee and gently start slide them up and down slowly and controlled past each other. Careful of dropping your legs too low, you can kick high up but don’t drop them too low.
The stronger your core section gets, the more your movement will decrease (until your legs are slightly off the floor with small sliding movement).