No matter what you may have planned, or how cool or timely it may be, or how exactly it may fit into the material you had planned to cover that day, you’re going to run into a situation where something goes awry. Perhaps it’s a technology issue at work, and that great piece of software you were going to demo just isn’t going to work on the classroom computer. Could be that for some reason, half the class just didn’t participate in the online exercise you had so meticulously planned. What if you have been assuming that an exercise was going to go one way, only to find that it has gone in a completely unanticipated direction?