Education these days seems to be about signals. What did you get on your SATs? How many AP classes did you take? What schools did you apply to? What extracurriculars did you practice? Even some of the modern strain of political correctness, critics have said, is really just a way for people to prove that they are more educated than other people–that they were taught the right words for this and that.

But of course, most of that is not education. That’s school. That’s symbolism over substance, noise not actual signal.

So what’s a real sign of a smart person? Well, curiosity is one, as we’ve talked about. So are projects–things kids have actually done, made, created, thrown themselves into. Here’s another one, noticed by the biographer Merle Miller as he sat down and interviewed Harry Truman, possibly the last American president to never go to college.

As they talked for hours and hours, Merle noticed that Truman mispronounced a large number of words, which puzzled him at first. “Then I realized,” Miller later wrote, “that while he had often read them, he had seldom, if ever, spoken them aloud, not even in many cases heard them spoken aloud. It’s like that if you’re one of the few readers in town.”

It’s great to hear your kid come to you with stuff they heard from their teacher. But if your kid is coming to you with words they discovered on their own, that is a sign they are learning. Like really learning. That’s a sign they’re going to be smart, that they have picked up the most wonderful habits in the world: Curiosity. Reading. Autodidactism.

Do your best to encourage it…and never, ever make fun of it.