The thing is, I am a teacher (although a long time out of the classroom).
I went ot school in the 70's and learnt not one line of gramar at any point.
So I have taught myself, and there are still some things i get wrong, and I know, so I check. Every single time. I have taught myself and learnt the rules for apostrophes etc.
I might have decided not to bother, BUT I was a TEACHER and needed to TEACH the children in my care. I made up things to help to remember the rules and the exceptions, because, as a teacher, it is my job to get it right.
No, it is not acceptable, as I said up thread, once, in a letter home, maybe. But like this, where it is the whole central concept of the task, no.
Poor kids, all that effort for something which ends up looking crap, reinforcing a mistake, and making parents doubt their own spelling!