Yep...a simple letter written is washable marker on the hand seems to do the trick. I've found that I only need to write the letter for about a week before the students are able to write the letter correctly on their own.
Now when it comes to a student with multiple reversals? (Which they usually have!) One letter at a time. I don't move on until they conquer one at a time. If the letter is in the child's name, I'll make that letter the starting point.
Why does it work? I honestly think because it's a constant reminder ATTACHED to them and at very close range. Really!
If you haven't tried it, give it a shot and let me know if it helped.
On another note, hope you don't mind if I show off John's latest artwork. I so wish I could draw! Have a good night!