Alan Borsuk:

Carolyn Bucior now has greater respect for classroom teachers.
She also has a greater sense of annoyance at some teachers.
And she has a grasp on a generally ignored issue in education that has led to her voice being heard nationally.
Substitute teaching is usually looked at somewhat benignly as one of those things that is part of school life. Like everyone else, teachers get sick sometimes or have other reasons to be absent. So someone gets called in to fill in.
I suspect everyone knows this is unlikely to be productive. Goofing off (or worse) when a sub is in the classroom has been a staple of student life since schools were invented.
You have to have an adult keep an eye on what kids are doing, but to expect education to move forward when someone steps in cold is rarely realistic. Well, maybe to watch a video the teacher left behind.