I remember it like it was yesterday.

On a grassy patch on the National Mall in the center of our nation’s capital, the party is over. The Capitol is on one end; the Washington Monument is at the other. And yet, all I can think about are these metal chairs. All 25,000 of them. They are going away now. One by one, they are being folded, stacked, and carted over to the event trucks parked on the nearby streets.

Just minutes ago, this sunny day was abuzz with excitement. The band was playing, the bagpipers piping, the color guards marching, the flags waving, the speakers speaking, the cameras flashing. And then, suddenly, the happy graduates tossed their caps into the air, and when they came down, it was over. The crowd lingered for a while. Congratulations hung in the air. But now all that’s left to show is a platform being dismantled one piece at a time and these metal chairs.

One of which I’m sitting on as I think about my son and all of us who have ever graduated. We worked so hard to get to this finish line, to walk up on that stage, to receive that handshake and that diploma. And then, just like that, it all changes right before our eyes. Our dormitory closes. Our classmates go off in different directions. Our professors head off to do whatever it is they do in the summer. We swear we’ll keep in touch, but we know that nothing will ever be the same.

And it won’t.

It’s as if the rug has been pulled out from under us. Even the metal chairs where we were sitting just moments ago are gone, leaving us to, well, stand on our own two feet.

This is nothing new, of course. We graduated from grade school and from high school. Every time “Pomp and Circumstance” ended, it was time to move on. Like an advanced round of musical chairs, we were left to jockey for our next position. Except in this particular game, the circle grows wider, the amount of ground we need to cover keeps expanding, and the expectations of what we’re going to do once we get there soar higher and higher.

There are those who would tell us that even with all that education under our belt, we weren’t ready for the “real world.” After all, for the most part, all we had ever been was a student. All we’d ever done was listen and learn. Read and remember. Calculate and contemplate. Invent and imagine.

If my experience is any indication, chances are we haven’t seen the last of those metal chairs. Just when we least expect it, just when everything is going along just fine, things can change without warning: The strained look on our boss’s face one Friday afternoon, just before we learn that our company no longer needs us. The awkward moment when our spouse says it’s just not working out between us.

Even if our personal life goes along swimmingly—and I so much hope that it does—there’s the world to contend with. Just a few miles from here, on the western lawn of the Pentagon, there’s a memorial to those who died there on September 11, 2001. It’s a sobering reminder that we never know what’s going to happen. No way to know which chair we’re going to get when the music stops.

But then again, we’ve been preparing for this moment of uncertainty, this crossroad of boundless possibility, since kindergarten. I am not worried. I’m optimistic that we’ll keep rising to the occasion. And this I hope for us all. That we’ll keep on listening and learning. Reading and remembering. Calculating and contemplating. Inventing and imagining.

The world is our classroom now.