Eyes to the front! You there in the back — sit down!
Discipline is the cornerstone of the educational process. It originated with the Latin praecipere, praecept, "to take before." Thus were created the precepts, i.e. those teachings placed "before" or "in front of" students.
Disciplina was instruction emphasizing the practice necessary to fully grasp those precepts. And there was no better group to spread them, dis, "around" — than a group of disciples.
According to the disciples of discipline, it's still the purpose of discipline — to create the proper context for dealing with the disciplines or "major areas of knowledge." We know it and welcome it today as the "maintenance of order."
In the 1970s we "welcomed" back Gabe Kotter (Gabe Kaplan) to his old alma mater, via national TV, as teacher of the undisciplined "sweat-hogs," a group of hopeless underachievers who personified for many what urban students were like.
This public's perception of students as animals then contributed to the hue and cry for even more classroom discipline.
Unfortunately, the discipline required to train them derives from the Latin trahere, tract-, "to draw," or "pull along."
Educating them comes from the Latin ex, "out" and ducere, "to lead" — a real education being the process that draws out those talents already within.
Anything less would be a real drag, man.