--I tell my students at the beginning of the year and remind them often that "language is a big mountain and we only know the paths we have explored." When someone knows or does not know something from a different teacher's class, I just say, "they were on another path. This is the path that I value." No need for insecurity or feeling dumb, etc. The main thing is to enjoy the journey, because this mountain will take a lot of exploring to discover all of the trails.--
I would have liked to have this beautiful metaphor in hand when my Spanish 1 and 2 classes all got jumbled and mixed at semester. I was worried that some kids would feel dumb that they did not know the word for "shark" or "hunts" or "tongue" or "dances" even though many of their new classmates seemed to have mastered it and would use it regularly.
Based on questions I fielded the days leading up to the big switch, I sensed a some students were a bit concerned as well. It turned out to be a complete non-issue. On the contrary, it was a blessing, as it allowed them all to learn from each other. They seemed to delight in showing off words they knew and stories we had created to the other students who were formerly in a different section. Within a few weeks each new class had arrived at a more homogeneous place... though we know that our classes are never truly homogeneous anyway. How boring would that be?