Lie face-down on the floor with your legs extended and feet about shoulder-width apart. Press your hip bones down into the floor, and bend your arms out to the sides so they form a "W" shape.
Keeping your spine extended and your gaze down at the floor, raise your torso off the floor. Instead of crunching up, think about elongating your spine and pulling your shoulders down away from your ears.
Slowly lower your torso back to the floor. That's one rep.