I taught a night class that met one time a week (15 meetings), for three hours. A student missed twice because his kids were sick, once because he had to go to a recital, once because he had to go to a hockey game. He missed the equivalent of four weeks of classes for his kids. He assumed that I would teach him, one on one, what he missed. He was astonished and upset when I told him to read the book and get the notes from one of his classmates. Many parents put their kids above everything else; some parents assume that their kids are that important to other people, but missing the equivalent of four weeks of class (for any reason) destroys whatever learning was meant to take place.
An earlier poster wrote: "My empirical data suggests that [students with children], as a cohort, attend more regularly and perform significantly better than "traditional" students." I agree with this, but it's correlative, not causative, and (in part) due to small sample size. People who have children and go back to school strike me generally as more mature than students without children; it's possible that parents who choose to go back to school are drawn from the more mature half of the set of parents as well. That being said, there do seem to be a number of parents who expect any kid-related dereliction of academic duties to be cheerfully waved off by the professor.