Abdominal  hollow/ posterior pelvic twist

Step 1—Lay on your back on the mat.
Step 2—Bend your knees to a 45° angle with your feet on the mat.
Step 3—To begin you are going to tighten your stomach muscles (your abs) this is your abdominal hollow.

Step 4—While your stomach is still contracted you are going to tilt/rotate your hips toward your upper body(the lower half of you back should be pushed up against the mat).
Step 5—Return to relaxed position, then repeat steps 1-4 for the amount of rep you are assigned.

Clams

Step 1—Begin by laying on the mat on your side.
Step 2—Bring your knees in at a 90° angle.

Step 3—While keeping your feet together, lift your top leg as much as you can (refer to figure
Step 4—Return your leg back to the resting position.
Step 5—Repeat steps 1-4 for the amount of rep you are assigned. 
Step 6—Complete this process on both sides of your body.

Crunch

Step 1—Lay on your back on the mat.
Step 2—Bend your knees to a 45° angle with your feet on the mat.
Step 3—Cross your arm across your chest or behind your head (if your hands are behind your head be sure not to pull up on your neck when you do the crunch).

Step 4—Lift your shoulder blades off the mat bringing them towards your knees.
Step 5—Retun to a relaxed position.
Step 6—Repeat steps 1-5 for the amount of reps you are assigned.