Students are so cell phone obsessed that besides dealing with basic disinterest (usually with young students 18-22), it is very difficult to hold students attention for long. Immature students expect to be entertained for an entire class and cannot seem lost if they are disengaged from their cell phones for more than 5 minutes. It's very disheartening as a teacher. Any suggestions?

Every class, especially large classes, have a number of students who are "taking up space." They clearly don't want to be in school, do the bare mininum, are disruptive in class and serve to bring interested students down to their level. What is the best way to deal with them without resorting to running a college class like an 8th grade class?