This version of the crunch works both the upper and lower portion of the abs.
Steps
Lie on your back and bring your knees up to a 60 degree angle, keep your feet flat on the floor.
Place your hands on either side of your head (over your ears). Curl up raising your right elbow and your left knee so that they touch over your chest. Return to the starting position and repeat with alternate arms and legs.
Tips
Contract your abs as you twist during this exercise.