HOW, WHERE, and WHEN can be relative adverbs according to Oxford. What I don't understand is the following: "How" is a relative adverb=in any way in which e.g. I'll do business how I like. "Where" is a relative adverb=in a or any place in which e.g. Sit where I can see you. Why is "when" a conjunction when it means at the time that? e.g. I loved math when I was in school. These are definitions and examples from New Oxford American Dictionary. Is "when" a conjunction because it is not uncommon to see it at the beginning of a sentence (e.g. When I was in school, I loved math)? I would appreciate any theories you may have. Why does Oxford make such distinctions? Note: Macmillan Dictionary defines all of the above as conjunctions.