I took a few secondary education courses after I finished undergrad work. In those classes, I often heard the saying: "Teach 'em where you find 'em."
Unlike some other popular maxims in contemporary educational circles, this one is actually valuable.
As a novice teacher, it's easy to go into an eleventh-grade English classroom thinking that one's job is to teach eleventh-grade English.
That's not good pedagogy.
Since the death of "tracking" by ability in American education, some teens in the class may be advanced and thus require enriched instruction. Others may be behind (and this, unfortunately, is the more likely scenario in today's classrooms).
When I taught English to high school juniors, I had a few students who should have been in AP classes and a number who were learning disabled. The rest occupied the entire spectrum between those two extremes.
My solution was to teach the class so that it would be interesting enough for the gifted kids, while making the tests and assignments flexible so that almost all of the kids could pass with hard work. Almost all the kids. One of the great injustices of the elimination of tracking and vocational programs is that two or three kids among my one hundred students were bound to get D's and F's because they simply could not handle the material mentally, no matter how far I dropped the bar.
I'll never forget one incredibly sweet boy who sat with me for an hour in a private tutoring session, doing his very, very best to understand the difference between an adjective and an adverb as I tried a number of strategies to teach him. Even in eleventh grade, he simply did not have the abstract thinking capability to master abstract categorization like the basic parts of speech. That boy did not fail my class, which may give you some idea how far I weighted the assignments towards effort instead of achievement. It's not a low-ability student's fault if the powers-that-be have arranged the system for his failure. Not every student should be required to master the same sets of skills; the idea that all students should learn advanced algebra is politically-correct foolishness. But because in America we must pretend that all students are the same, in order to avoid offending anyone, we have damaged students' chances of learning what they need to know.
We cannot track our students by ability, so it is up to each individual teacher to somehow try to educate the widely-varying assortment of students who walk into her classroom each year.
Any teachers who really cares about teaching eventually realizes that the classroom situation may be ineffective and unwieldy, but as the old anecdote goes, you can only save the starfish by throwing them back in the ocean one at a time.
Whether a student requires intellectual challenge, reinforcement of basic concepts, carrot, or stick, the teacher must figure out the need and meet it. During my time in the classroom, I found that the best teachers are those who understand that teaching is a study in human character--that the most important task of a teacher is to discover what makes her student tick. Without that knowledge, no meaningful teaching can occur.
"Teach 'em where you find 'em."