We've been trying to teach our son to tie his shoe laces all summer. He wears a size two shoe these days and finding velcro shoes in this size is getting really hard!
He's found it tricky, and we think it's because he's left handed and we've been trying to teach him in a right handed way. Husband switched to showing him using his left hand as the dominant one (how he did it, I have no idea!) and bingo, son got it in just a day or two.
Today, he tied both shoe laces for himself and was made up with himself. To him, it was a massive achievement and he can't wait to show his best mate when he goes back to school.
So if your left hander is struggling to learn, try tying shoelaces backwards yourself or have a look on YouTube for a few different videos which may help.