Kicking Drill - Wall Kicking
This video from Swim Technique TV that demonstrates an easy, helpful drill for those swimmers who are unable to kick using a kickboard. I am posting it here just to show you how the drill is done.
You can either keep your head out of the water or put your head in the water and lift it to breathe (which will help with body position...remember, when you pick your head up your hips/butt sink, which cause your legs to drop). Do your best to keep your butt at the surface of the water, maintaining your body position, so when you kick freestyle your heels just break the surface of the water, making it "boil".
As you can see in the video, you can do this drill for all four strokes.