My classes are between 65 and 100 minutes long each. In the final minutes of each class, people would start packing up their books and things as the professor is still talking. Often, the professor will need to raise his or her voice to be heard in those final minutes.
In high school, I had a teacher who condemned this practice. “It’s rude to everyone for you to start packing your things. The class isn’t over until right at the time it ends. I will agree to try to cover the material and not go over time. You need to agree to not disengage and start packing things away until class is officially over.” When people would start packing their things before time, she would say “Stop rattling! We’re not done.”
I still remember that lesson now, and do my best to remain engaged during the entire class time. I also wonder if any professor would call a student out for that. “So to recap, as we discussed in Pierson v. Post today Mr. Kim please stop rattling, you’re making a nuisance. Class isn’t over yet.”