rough
through
though
tough
thorough
enough
slough
although
dough
sough
hiccough
bough
cough
furlough
plough
borough
One thing that most smart teachers agree on, avoid the exceptions and the difficult words for a few years, maybe five or 10 years.
Later, when you’re doing 50 things correctly, you can handle the oddball situations one by one. I think most people absorb a great deal of weirdness, linguistically speaking, without knowing it is weird. For example we do this routinely with foreign words and unusual names. People are entitled to spell their names any way they want. It’s our job to accept it, learn it, and don’t make a big deal of it.
I notice a hostile tendency by our Education Establishment to fuss over the weird words, so they can reach the conclusion that English is a nutty language and not phonetic.