I'm copy-editing something right now, and I am coming across a problem I saw in college when I edited for the YDN.
Two spaces between sentences.
Stop it. Stop it right now. Don't teach kids to do this. Don't do it yourself. It is wrong. No one publishes articles, stories, or books with two spaces in between sentences.
SO PLEASE, PLEASE STOP IT. I am feeling particularly frustrated right now. I could kill whatever teacher taught this writer to do such a viciously incorrect thing.