Some back-to-school food for thought: In a recent post on her Center for Teaching Quality blog, Ariel Sacks says that, despite her original "cool teacher" instincts, she has gradually learned that "sweating the small stuff" in terms of student behavior and comportment (within reason) is not something to be scoffed at. To illustrate, she lists five "pesky" behaviorsthat she no longer allows in her classroom. Number one is "loud entry into class." She explains:

In most schools, students tend to be loud in hallways. Hallways and classrooms, however, are two distinct spaces, with very different functions. The way students enter the classroom sets a tone for themselves and their classmates for the period. What's the tone of an ideal learning environment? I ask students. How does it feel? It might be happy and upbeat, but it needs to have space for quiet thinking as well. Shouting as one enters a classroom doesn't create the tone of the learning environment we want. Whether you require a silent entry or just a calm one, it's worth having some talking points prepared when students test the boundaries. 

All of Sacks's strictures, incidentally, have that same emphasis on preventing distractions and establishing her classroom as a place apart from the restive outside world.