During a group homework pow-wow, I found out that most journalistic writing only uses one space following a period at the end of a sentence, not two. I have been using two all of my life, and have done it on my assignments also.
Doing a little research, I discovered there has been long running debate on whether to use one or two spaces after periods. It seems the two period method began in the days of typesetting to make sentences stand out from each other. These days, computer fonts eliminate the need for the extra space automatically after one space, so sentences with only a single space following the period should still stand out enough to the human eye.
I remember as a kid doing his first writing assignments on a typewriter (I think I wrote an essay about spiders in third grade) and my mother told me to put two spaces after each sentence, because “that’s the way it’s done”.
Apparently there is a movement to eliminate the two space method, but to me it seems like a push. Some can use one space, some can use two, who will really notice? It’s like “cannot” and “can not”. Both are correct (when used in the correct context).