When Did This Happen?

I picked Erma and her friend Antoine up from the mall today, and brought Antoine home. There I saw her brother (Scout's age), looking like a teenager, bringing in the groceries. Meanwhile, Scout and a friend were at the movies all by themselves (1st time), and I thought, when did this happen? Just yesterday, Erma and Antoine were in the backseat, singing the fire engine song that they learned in preschool. And I was thinking about how preschool was such a big step. Scout and Antoine's brother were toddling along as we'd pick up their big sisters from school...
And all of a sudden it's ten years later, and I don't know where those little kids went.