Factors that are important in effective teaching are:
• discipline in the class
• full attention on the topic of discussion
• teaching in an impressive manner
• relevant black-board work
• good classroom communication
• congeniality, accessibility and patience of the teacher
• education and knowledge base of a teacher
If teaching is effective, students are attentive; they understand and enjoy the lesson; and, complete assignments successfully. This leaves little room for disturbance of any kind or need to punish anyone. So, punishing students is the least important factor in teaching.