RE: "You are not an old lady."
If you're saying, and it would appear you are, that being an "old lady" makes her inadequate to the task for which she was hired, one must then fault her for accepting a job for which she was inadequate, and Human Resources for hiring her.
The kids were unquestionably at fault, but according to your statement, so was she and the school system who hired her, for giving her responsibilities she was inadequate to handle. If he/she could do the job for which he/she was hired, I'd have no problem hiring a 90-year old - if he/she couldn't, I would either never have hired him/her, or once hired, would not have kept him/her in that position. Neither age nor sex should be a factor - they can either do the job or they can't. Clearly she couldn't, but excusing her on the basis that she was an "old lady" is absurd.
Your entire argument is premised on the assumption that it might be anticipated that these boys would act as they did. I seriously doubt that there was any discussion of having to put up with anything like that sort of behavior as part of her job description.
So you're saying that a person or organization, responsible for running an entire school system, knows that little about the potential behavior of kids?
And we're paying them?
I don't think we can expect any school system to be prepared for any potentiality. Like most organizations most of the time, they (like us as individuals) prepare for what's likely. The category of potentialities borders on the infinite, and no one can prepare for that.
Assuming you know at the time you take it that you can't do it. And then, once someone has a job, they will want (and NEED) to hang onto it until the next opportunity comes along.
Besides, no matter what your skills and abilities, there are days when the job may throw you more than you can handle. This goes for a 20 year old needing to meet rent, buy school books, and make a car payment, not just an elderly worker.