One and Two-Knee Drills

This is a great way to teach proper arm mechanics and build arm strength.

One-Knee Drill:

Have players start about 15 feet apart with their strong knee on the ground. On your signal, the player should break properly, with their elbow just above their shoulder and ball pointed backwards or "ball-to-the-wall." On another signal, they should throw, following through completely. Repeat by switching legs. A variation on this can have them follow through and then do a pushup, returning to proper position.

You can also back them up once they are warmed up, but don't go too far.

Two-Knee Drill:

Do the exact same thing as above, except have players on both knees.

* The break-and-throw part is the most important part of all this.
** This drill eliminates all leg motion that can possibly affect the mechanics poorly.