Beats me how you can justify a teacher forcing a child to switch hands. When my mother was a child (yes, in a one-room schoolhouse), she was forced to switch and become right handed. I asked her why she didn't simply switch back, and she said she'd been writing so long with her right hand that she really couldn't. She always struggled to write neatly.
When I entered first grade Mom told me that if the teacher tried to make me use my right hand, to tell the teacher she'd be having a conversation with my mother. That's exactly what happened, I think the teacher was taken aback that a small child would stand up to a directive like that. Mom and the teacher spoke (I was not privy to the conversation) and I was never asked to write right handed again.
I also learned to shoot right handed, and was disturbed by an earlier poster who apparently thinks shooting a gun is wrong for some reason. My parents gave me the best gun safety education a child could possibly ask for, and safety has always been #1 for me when around firearms. Anyway, the rifles we had were bolt action and of course were made for right-handed shooters. I really had no choice but to learn to shoot right handed, and I do so now. I'm strongly left eye dominant, being naturally about 20/40 in the left eye and 20/200 in the right eye. Didn't have glasses as a kid (that's another story), but had to learn to shoot using my weak eye.
Interesting about writing, I saw a few left handed kids that wrote with their hand all scrunched up, and it made no sense to me. It was like they were trying to be right handed with their left hand. Being fairly inventive, I adopted a natural position of the hand and taught myself. My teachers were no help, and they probably secretly wanted to force me to "write properly" with my right hand. Learning to take my own path and not blindly follow instructions was a great lesson in life.
Ever notice how pretty much all paper forms are totally right handed? When I'm handed a clipboard with forms to fill out, I unclip the paper and turn the clipboard 90 degrees so that my left hand has support while filling in blanks that are at the left margin of the page. Funny how there are few if any blanks to fill in at the right margin. I laugh every time there are and some "rightie" complains they're hard to fill in. Welcome to my world, dude!