make sure you keep your back strait, and that your knees don't go over the toes, your hands can be interlaced behind your head, on your waist or down at your sides like in this pic
once again feet shoulder with apart, and make sure your knees doesn't go over your toes.. try to keep your butt back ;) like your trying to go pee on a yucky public restroom and don't want to touch the seat...
lay on the floor legs in the air and use your lower ab muscles to lift your bootay off the floor this targets the lower abs where we tend to carry most of our belly fat
even if you do them on your knees you want to make sure you keep your back strait and allined w the legs, make sure you "break the plane" as in your chest dips down low enough your elbows are above your back
with whatever weight you choose to use start by holding them parallel to your shoulders by your ears and just simply push up
bicyle ab exercise
you move your legs basically like a bicyle each time you bring a knee in the opposite eblow crunches up to meet it, you work your obliques upper and lower abs so its a good one, and you WILL feel the burn!
once again you grip the edge of the chair, or table whatever and using your tricep muscles lower your bootay down, keep it close to the table or chair to isolate the muscle you can also do these on the floor but they arn't quiet as effective
holding the dumbell or soup can, you use your bicep muscle to bring it up to your chest, make sure you use controlled movements up and down
crunches are so easy to do the wrong way, i like to do full on sit ups, you can have your kids or spouse hold your feet or you can put them under the edge of a chair or door