From
Brian P. Cleary
Reason #234 that English is a hard language to learn: the –OUGH sound. “Though he had a rough cough, he still thought he could jump through the air and touch the bough of the tree.”
More from Brian P. Cleary:
Most people have trouble remembering how to spell one word or another. When I was a kid (long before spellcheck) my enemy was "necessary". It was mostly the C' and S's ...how many of each? So I came up with "1 COAT, 2 SHOES" to remember 1 C and 2 S's. As a grownup, I wrote a whole book of these tricks.