Too many times today, kids are the discipline in their homes, and they have no frame of reference for effective discipline. Not necessarily the "follow the rules or I'll beat you" discipline, but the discipline that is administered with love, with a goal of making them a better person. This is not necessarily relevant to the teacher beating the kid, but it was an awakening in my professional life...
My first teaching job was at Central High School in Tuscaloosa. I was fresh out of graduate school and knew everything and was ready to change the world. I was 21 years old and teaching a class of 18 year old, mainly inner city, Tuscaloosa kids. A few weeks into the job, I had this one student who would not do any work, and when I would reprimand him he would have a smart aleck comment and basically blow me off.
I finally had enough and did a discipline report on him. Next day the assistant principal called me into his office to talk about it. I was adamant that the kid had no discipline, was not responsible, was going to fail and end up selling drugs, etc. The administrator agreed with everything I said, and let me know that he supported me 100% if I wanted to go through with the write-up, but that it would likely lead to the kids expulsion, due to an accumulation effect.
Then he told me about the kid I was writing up. How he had been the man of the house since he was 11 years old, so no, he didn't do well with male authority figures. His mother was in and out of metro jail on prostitution and drug charges, and this kid had been raising his 4 younger siblings since he was 12. He asked me how many teenagers had the responsibility and discipline to do what this kid does day in and day out. Heck, it sounded like something out of a movie. But It changed my entire way of looking at the world and made me a much better teacher and coach.
From that day on I tried to make it a point to know my students on a personal level. Not necessarily trying to be their friend, but understanding where they are as a human.