I know it is shocking, but most of the times teachers know when you are looking at your phone! So do not be surprised! Phones are a huge distraction! It is ok to be away from it for a length of a class! I heard a student say last year that when she does homework she puts her phone away because it is too distracting! And I would guess you would get your homework done faster if you did that!
It always surprises me how many students turn in a paper with no name! Before you turn in a paper - make sure your name is on it!