Since the weather broke, we've been allowing Maxon, who is 11, and Ezra, who is 8, to ride their bikes and scooters around our neighborhood just south of Center City. I set boundaries, which includes the playground up the street. In the afternoons I can see them see them whiz past the kitchen windows as I'm cooking dinner, a blur of hoodies and hair, and I remember what it was like to speed through my mother's suburban neighborhood unsupervised, as I often did because helicopter parents didn't yet exist.