Forever

I know how long eternity is: five minutes. I know this because I work at an elementary school. When things get tough and a kid forgets how to play nice, I'll give him or her a warning. If that doesn't stick, then he or she will get to sit on the bench. For five minutes. The good news is that most of our kids know that sitting on the bench for five minutes is purgatory. The next step toward damnation: an entire fifteen minute recess on those awful green benches next to the bathrooms. Everyone else is playing four square, or soccer, or wall ball, or racing about in circles, screaming at the top of their lungs. Has it been five minutes yet?
If there was anything longer than the five minutes that those nine-year-olds have to sit on the bench, it's the time it takes me to explain and remind and explain again how long five minutes is. It's three hundred seconds. How hard could that be? Just count to three hundred. Okay, you can't just count to three hundred. You have to include the Mississippis. Or Bananas. That's the only way you can be sure that it really has been five minutes. Of course, as a skill, there aren't that many elementary school students who can count to three hundred. Not that the concept is foreign. They understand cardinality. They're students, after all. Mathematics are not the problem. It's patience.
The kids who have a limited supply of patience are probably the ones who used it up already with their classmates. The ones who wouldn't get out of the way when it was time for less-than-patient-child to climb up the playstructure ladder. The ones who don't understand that being "out" is part of the game of four square. The ones who might possibly burst into flame if they had to stand in line for anything. What is the consequence for losing what little patience they might have is to test it even further by having to sit still for five minutes. Forever.
Here's another piece of elementary school wisdom I only recently acquired. When I am dismissing a class, I tend to wait for students to be settled in their seats before asking them to line up. This means that the calm and settled group is the one that lines up first. The squirmy, fidgety kids are the the ones who line up last. That means the front of the line is loaded up front with the kids who can stand still for whatever time it takes to get the rest of their classmates to queue up behind them. Interestingly enough, this process takes about five minutes. Forever.