Ab days are one of my favourite so here is my ab day workout!
SET 1:
15 leg raises
15 Russian twists
15 forward crunches
15 crunches on each side
30 second plank on the front, and on each side.
SET 2:
15 leg tucks
15 bicycles
15 reverse crunches
30 second plank on the front, and on each side.
SET 3:
15 jackknives
15 flutter kicks
15 heel taps
30 second plank on the front, and on each side.
I repeat each set 3 times but adjust according to your fitness level!