You may begin to recognize a trend with these exercises -- there are no sit-ups or crunches to be found, and with the exception of planks, each exercise uses some sort of cross-body engagement that involves stabilization of the spine and contraction of the entire abdominal cavity.
Woodchoppers are no different. But unlike the other exercises on this list, woodchoppers add a diagonal full-body rotation to further target the obliques while mimicking movements used frequently in sports and daily functional activities.
To perform the exercise, grab a dumbbell, plate weight, medicine ball, or anything semi-heavy and hold it in both hands in front of your torso. To get in the starting position, press your hips back, bend your knees, and squat down slightly (not a full squat), rotating your body to the right until the dumbbell is positioned just to the outside of your right knee.
Keeping your arms straight throughout the exercise, tighten your core and extend your knees and hips to stand up, and as you do, "chop" your arms diagonally up across your body, reaching the dumbbell over your left shoulder. Reverse the movement, and as you return to the semi-squat, "chop" the dumbbell back down and across your body. Make sure you really use your abs to control this cross-body motion to keep your spine neutral throughout.
Aim to perform three sets of eight to 12 reps to each side. If you're new to the exercise, you may want to start without weight, just to master the movement before making it more challenging.