You’re 45 minutes into your Algebra 2 final when all of a sudden your pencil stops working. You look at the end and see that there’s still lead in the pencil, so why isn’t it writing? You press the tip of the pencil down onto the page and the lead vanishes back into the pencil. Now you’re annoyed. You repeatedly press down on the end of the pencil, trying to get the lead to come back out, when a little piece of it falls out of the pencil and onto your desk. There’s not much left, but there’s definitely still enough to write with. However, you know from experience that that’s not going to happen – that little piece of lead is now totally pointless. Now you’re stuck in the middle of taking a final with no pencil, which, of course, will cause you to fail the test and the class, which will lead to you dropping out of school, resulting in your entire life being derailed. All because of that little piece of lead.