"So far, nobody did study them, but it works. It's a machine pulled by ropes." He reads one side of his key to figuring out his floor number, and he pressed a button of the number that corresponds to the floor.

"I'll show you when we get there." He follows him to his room and shows him how to use the card. "It is your key to open the door to your room."

Voila, the door opens to his room, just like that. He stood there patiently if he has any more questions.