The great thing about kids is that they can make a game out of anything. As much as they are currently addicted to iPads and ritalin, if you throw them a stick they'll create a fun game to play (or they'll poke their eye out, but you gotta learn somehow). I remember being a kid and my dad would bring a big piece of cardboard home for us to draw racetracks on. It makes my childhood a lot of fun to think about, as long as I forget about all the Winters we were too poor to eat.
This babysitter had a great idea to keep the kids entertained while getting a little rest. Let's just hope those trains don't go off track and end up parked in his caboose. That's a tough hospital visit to explain.