A linguist friend recently contacted me with their daughter's orthographic observations:
"So my daughter just noticed that <or> sounds like <ir> and <er> in some cases but not others," they wrote. "E.g., word, bird, herd, worm, work, etc. But not others, e.g. corn, horn, born, pork, cork, etc. Then she noticed that all of the <or> as schwar words start with <w>. Then she came up with worn and thought maybe that's an exception because it's a past tense. Do you have a post on this already?"
"I don't have a post," I responded, "but I can explain this pretty easily." I did, and then I asked for permission to share the inquiry here. Permission granted, so here's an understanding of spellings for rhotic phonemes in English:
Getting Control of Rhotic Spellings
"Spelling is so multidimensional," said my friend. "There's grammar here, etymology, lexical phonology, and prosody.""It's everything," I agreed. "Spelling is never just spelling."