Many (many) years ago, my high school typing instructor insisted on two spaces after a period. This rule was immutable. My kids thought this was ridiculous when they started doing homework on the computer. And I thought their insistence on one space after a period was rebellion that would pass. Well it turns out that they were right. Even the Chicago Style Manual backs this up. Two spaces creates awkward line breaks on digital media and even in print, is no longer thought to improve readability. If only I could get my thumb to stop hitting the space bar twice. Who knew.