After many years, I moved up in the world of education. I gradually got to teach classes that were on track and even spent many years teaching AP calculus. My years of teaching the lowest level helped me reach the brightest kids. My years of teaching remediation had taught me that what was obvious to me was not obvious to them. What interested me did not interest them. I learned to break down difficult material for advanced students the same way I did for my strugglers.
While teaching advanced classes, I still had repeaters and slow learners in my other classes. Teaching the top helped me raise the level I taught these difficult kids, the kids who repeatedly failed and who did not care for math or any school subjects. They needed to be taught on a level that showed I respected their intelligence and their ability to learn.
To be a good teacher one must teach all levels at some point in her career and should even go back and teach courses out of the norm to keep the brain alive and productive. A good teacher must realize that there are students with many different learning levels. A teacher who never teaches an honor class might start to believe a mediocre student is brilliant while a teacher who only teaches the top might not have enough respect for the poor child who struggles with calculus.
Most teachers have 5 classes in a NYC high school. Although I often had classes that were a challenge, I am glad I had them. These classes made me a better teacher for the advanced classes. The advanced classes motivated me to find higher levels to reach everyone. Everyone should teach a mix.