After less than 2 months, the dreaded 3-month evaluation

Whether or not my teaching career will continue all comes down to today's music class. Only a score of 75% or higher is acceptable.

Murphy's Law states that one of three things will happen.

1. The class is especially rowdy, and I cannot control them. I fail the evaluation for not being able to control the kids.
2. The class is so young that they cannot understand a word I say. I fail the evaluation for not being able to get them to do/say anything.
3. There are no students in the class, and I have to do the class for the evaluators! This makes it impossible to pretend the evaluators are not there, and I crack under the pressure and fail the evaluation. (As this is probably the worst of the three, as the evaluator will most likely simulate one of the above two scenarios, and I won't have anywhere to look other than the evaluators who are constantly writing notes, this is also the most likely according to Murphy's Law.)

My whole career rides on a loophole in Murphy's Law other than dumb luck.