Man, I love the olden days. You must check out this vintage film, "Molly Grows Up" (available in several formats), with its classic take on menstruation. It's surprisingly modern in some of its approach, although full of outdated gems like "don't swim the first few days of your period or you'll catch a chill", "wear your prettiest dress", and a pass at the old "women are meant to be mothers" line of thinking.
Try not to be distracted by Molly's awesome Craftsman house and her family's kick-ass mid-century coffee table. Instead, pop some corn, sit back, and let Molly's mother and the school nurse (she's got to be Lauren Bacall's homelier older sister, it's an uncanny resemblance) tell you how it is in Periodsville, 1953 (hint: go easy on the square dancing).
If you're in the mood for a double feature, watch the 1957 companion piece, "As Boys Grow", where a jovial coach explains puberty to his team ("say, I had a wet dream last night!").