Almost everyone speaks in class, this is unusual. No penalty for not speaking or speaking often. Less 'ping-pong' talking and more lateral conversations between students. More reference back to the texts we're reading. A set of rules, techniques, or processes that controls group behavior in a systematic, deliberate way.
People then begin to believe it, taking it as fact.
Cultural controls are subtle and pervasive system of beliefs and practices. They take time to spread out and become accepted. Blaming student's personality or lack of willpower when they fail. Denies systemic barriers. Dickar's observations probably describe not just teachers, but also common strategies practiced wherever cultures intersect and one group is strongly dominant.