While I’m thinking about teaching and texting and distraction, here is a statement about decorum that I used (with variations) on syllabi over many years:
I see this statement not as harsh or threatening but as plainly serious. Students, with very few exceptions, saw it that way too. Texting, as you can guess, was a rare occurrence in my classes.
Webster’s Second does a bang-job on decorum. Sense 2:
A standard or code of what is fitting, proper, or established by good usage, in the relation of parts to a whole, or means to an end, or esp. of conduct to principles or circumstances; hence, propriety; the proprieties; “good form”; convention; also, a requirement of propriety; as, a breach of decorum . “So far from the common decorum of a gentleman, as to send a letter so impudently cruel.” J. Austen .The times, they change: at one point, my decorum statement mentioned knitting. Circa 1990-something, knitting in class was a thing.
[The decorum statement is in my favorite font for syllabi, Jos Buivenga’s Fontin Sans. After reading Edward Tufte, I began making syllabi with three columns running down the page; thus, the little block of text above. I made sure that a syllabus ran no longer than one double-sided page: compact and highly readable. If it doesn’t go without saying: exceptions to the no-phone rule were always possible, as when a student was waiting for a call about an urgent family matter.]