For that reason, kids usually wore their school clothes for at least two days.
Girls had to wear dresses or skirts to school, of course. After school we'd change to our play clothes, and those usually included jeans, slacks, or pedal pushers and a tee-shirt. Boys, too, would change out of their nice school clothes every afternoon and put on jeans for play. We'd wear the same set of play clothes all week.
We also had some nice clothes for dressy occasions like church, birthday parties, and holidays. Usually girls would have organdy dresses for warm weather and velveteen or taffeta ones for the colder months and boys would wear suits and white shirts. They also wore neckties, though the ones for kids were already tied and held on with elastic that went under the shirt collar.
Girls always wore slips with skirts or dresses and it was humiliating to have anyone see part of them. There were several code phrases like "It's snowing down south" to subtly let a friend know her slip was showing so she could rush to the bathroom and pull it up.
And if anybody saw our underwear we'd almost die of embarrassment because someone would be sure to call out, "I see London, I see France, I see somebody's underpants."
Now young people walk around with their underwear showing all the time on purpose.
I wonder what would happen if all us older folks were to shout that chant and point to them every time we saw those no longer private garments in public.