They used to teach us to put two spaces after a period, now it's one.
You must be young. When I went to school we had to still write everything so there was no such thing as two "spaces" after a period. Then again since I have left handed tendencies but was forced to write right handed, my writing was atrocious. My teachers were just happy if they could read what I wrote at all. On the upside I am now mostly ambidextrous.