Several other teachers gave me the same explanation for pushing two spaces on their students. But if you think about it, that's a pretty backward approach: The only reason today's teachers learned to use two spaces is because their teachers were in the grip of old-school technology. We would never accept teachers pushing other outmoded ideas on kids because that's what was popular back when they were in school. The same should go for typing. So, kids, if your teachers force you to use two spaces, send them a link to this article. Use this as your subject line: "If you type two spaces after a period, you're doing it wrong."