Life happens.  I teach classes to students who are entering or are already in jobs where my class is considered part of the career development.  They are not going to transfer to another school.  They do not want a degree, but one would be nice.  They are in the class to learn how to troubleshoot electrical circuits.  They also have a boss, employees they supervise, kids they watch, jobs to do, emergencies to take care of, cars that break, pipes that freeze, pets that die, significant others that want their attention, and a lot of stuff happening that I do not remember having to deal with when I was in college.  The extra baggage they carry in terms of distractions from the class can be formidable.  It is nice to have them in the classroom with their baggage left at the door.  The class activities need to be engaging, moving, interesting, or the other distractions are going to take priority.  I am challenged with making sure that the class was worth coming in for.  We have daily lab exercises.  The students are building circuits.  They are using test equipment.  They are not sitting for more than 25 minutes of formal instruction for a two hour class.   All the seats are not always full.  The students have other responsibilities that take them away from the classroom, even when they want to be there.  Students miss class, and we do not want to leave them behind.  Therefore, the format, pace, and activities have to be flexible, because life happens.