more than one roof
I spent most of today in a first grade classroom, and one of the things I helped the kids with was developing a programmatic understanding of pluralization in English. You know, s after most words; when a word ends with consonant-y "drop the y and add ies"; and the rule for when you need to add es. The style in schools now is to teach things like that explicitly, which is fine—there was a penguin on the printed sheet to provide a minimal amount of fun, and I don't think anyone felt their time was too much wasted. But in real life, pluralization is pretty automatic (see "wug test"). We don't really need to remember that es follows x, s, or ch... it just seems to make sense.
Of course, we learn those patterns automatically as young people, and it's possible for language learners to overgeneralize. Zion does! And when I think about it, I totally agree with him. He hears "batches" and thinks, fine, how about "pathes"? And if th, why not f as well? I'm a big fan of "roofes" (pronounced roofiz), which I think is yards better than the current confusion. Is it "roofs"? "rooves"? Horses have "hooves", right? Hmm, what was that I said about automatic pluralization? I take it all back. Can I have some direct instruction please?