Really? You need to come into my Y2 classroom then - my children know that if they encounter anywhere other than the beginning of a word, it's an alternative spelling for /f/. They do this automatically to read lots of words - laugh, photograph, enough. It doesn't cause them the problems you imagine it does - it's just part of the complex code that we teach them every day
Through must be a challenge for them then.
And how do they know which version of ou to use, without vocabulary, experience, and a little of trying out the different options to see which sounds right?
What you've done is teach them that it can be an alternative but they need to use their knowledge, vocabulary and experience to determine when it's appropriate. Which is great. But it's not pure 'phonics is everything you'll ever need' and 'you can decide anything using phonics alone' as some on this thread are evangelising.
If phonics was all I'd ever had, I'd still believe awkward and orquid were separate words, pronounced slightly differently, but with similar meanings.
Mrz, I'm not suggesting that. At all, and you'll recognise that if you read what I've said.
I'm saying that the insistence that phonics is absolutely all a reader of English needs to figure out how any unknown word is pronounced is daft, makes you look quite silly and undermines phonics to the average parent. Which is a pity - but perhaps you're one of those teachers who feel parents shouldn't be interested in how their children are being educated and the attitude and approach of the person doing it.