[keithpeter]

"If a cohort of students fail to reach their expected target then the teacher is usually considered responsible."

Or at least the alarm bells start ringing and there is a conversation (UK based myself). A 'cohort' is the word I usually use for a whole set of classes, e.g. a year group. More than one teacher is usually involved. We also have independent information on teaching through QA observations and OFSTED. Your picture is fundamentally accurate but it is a tad more complex in my experience.