I just remembered that the very first time I ever flew on my own, I had one of those. I flew AA from SAN-PHL, and I had one boarding pass. I knew we were stopping in ORD, but I had no idea I would have to get off the plane and go to a different gate. The things you learn by trial and error.

My bag apparently didn't know it would have to transfer, either, as this was my first delayed checked bag.