I subbed today for a high school science/geometry teacher.
I got another lesson plan saying, "students are working on a project. They know what to do." What made this one different is that it ended with, "if they finish early, they can just do homework or whatever." Today was the first day back from Thanksgiving break, and it was second period. They didn't have any homework.
Geometry student: "So, do you actually know how to do this stuff or are you just kinda here?"
Mr. C: "....[insert explanation on how to find the interior angles of a triangle]. Get it?"
Geometry student: "oh, yeah, thanks."
During the last class period we were watching an episode of a documentary series on the universe. Somewhere during the middle of it a kid comes up to me and hands me his phone with some puzzle game on the screen.
Kid: "Can you beat this level for me?"
Mr. C: "What? Are you serious?"
Mr. C: "No, and I'm going to just hang on to this until the end of class."