GagaJo
Why sandpaper NotSpagettic? Muscle memory?
That's right.
Sue Lloyd did something similar in Jolly Phonics.
I'm not sure how useful it is as you use different muscles when you write the letters with a pen/pencil, but at least it should help to instil the correct way to form the lower case letters.
I'd stress being particularly careful with the formation of b & d because those are the two that children get very badly confused (also p & q, but not quite so much). Letters should always be formed from left to right, so the order for forming it is ascender first, then the 'ball', whereas for d it is 'ball' first, then ascender. I have had so many Y7s who start both letters with the ascender and then have no idea which way to go next. It makes me so cross because they'd have no problem if they were properly taught from the first!
And all those little 'tricks' for eliminating b/d confusion don't really work because the child forgets them when they're concentrating on the content of what they're writing. The 'confusion' is a long instilled habit. We know how difficult it is to break habits...
Also, if forming or tracing letters try and get the child to say the main sound it represents as they do it.
Never teach letter names, they're not needed at this stage and it will get in the way when they start learning to read and spell. So, /b/ for 'baby, not /bee/ etc.