I remember when we were first learning cursive. My teacher insisted we start by writing in pencil, I suppose so that we could correct our mistakes. The rule was: once you received 3 compliments from her on your penmanship, you were allowed to write with an actual ballpoint pen. I hated writing in pencil, but I couldn't get a compliment. Not a single one. I fantasized about at least getting a paper back with the words, "You're getting better!"
Finally I did get that very phrase on the top of a paper! I joyously told her how happy I was that I only had 2 compliments to go -- but she told me that she didn't consider what she'd written a compliment. Showing improvement wasn't sufficient, it actually had to be good. I was devastated. Stupid pencils...I still hate writing with them.
Drood said he writes his 8's upside down, starting from the bottom instead of the top of the number. He was constantly scolded for it. I make my 8's from the top, but my O's and 0's start from the bottom. Surprisingly enough, my teachers never complained about that at least. I never even knew that was "incorrect" until somebody noticed it in college, I think.
On the other hand, I remember sometime in grade-school I noticed an 8 was an S with a slash. I started writing them with two strokes because I thought it was fun, and for one math assignment I actually decided to give myself a special treat. Since the slash was my favorite part, I did all my 8's as S's and saved the slashes for last.
When the arithmetic was done, I went through and gleefully slashed through all my 8's. I also remember doing that with writing now and then, saving all the crossing of T's and dotting of i's and j's for last. Except that sometimes I missed a couple and got in trouble.
For awhile I also tried writing my 1's with the little notch at the top, but my teacher thought they were poorly crafted 7's. She thought I couldn't add, but really it was just that I didn't want to write sans-serif.
Teachers never approved of my handwriting experiments.