I'm sure jlinger is a few years younger than me - my first typewriter had tiny pebbles as keys and we used dried Woolly Mammoth skin as paper - but I was also taught to always space twice after a period (full stop). In fact, in the US, most professional style guides of the 1970s/80s specified the same two-space practice. However, with the advent of word processors and proportional fonts, one space after the full stop has become the norm.