Expressing Dissatisfaction

One of my brightest students was also one of the most disruptive students during my unit on fractions. He does not act this way during the other subjects and I needed to express to him my dissatisfaction. Daily he could ask to use the bathroom, talk out of turn in class, play with his partner, not complete his homework, and not focus during lessons. During the middle of the 5th lesson, the class was out of control so I said the next student to talk out of turn would make the whole class have to complete a worksheet which had addition and subtraction of fractions, a skill not yet taught, and I would make them do it in complete silence. Sure enough, thirty seconds after I said this, he spoke up. I turned around, got the worksheets and handed them out, telling the class it was that specific boy who caused me to do this. The parent teacher conferences were a few days later which he was present for. I told the mother his focus and behavior is unacceptable and that I know he is capable of understanding the concepts, but he has to focus and complete his homework in order to do so. While I was expressing this concern,  he sat their silent, face down, with an apologetic and discontent look. The very next day, he expressed to me the first period, (math is the last period) that he had done his homework, that he wants to know how to find common denominators, and that he promises to stay focus in math at the end of the day. If I had known, with this particular student, how easy it would have been to make him to this, for all it required was a stern, blunt, truthful expression of dissatisfaction, I would have done this in one of the earlier lessons. Thankfully he had 4 more lessons to learn and try because he did so and earned himself an 83 on the summative assessment. Nevertheless, his homework and participation grade suffered, causing him to receive a C in math if I remember correctly, so the lesson stuck. On progress report day, he saw the C and the same apologetic, discontent and now dissatisfied look appeared on his face. I did not feel sorry for him however, since he now understood an important lesson.