Good teacher

What is the difference between bad, good and excellent teachers?

• Bad teacher provides to student right answer to student's question based on right knowledge. That decreases student's independence. Because in the future, the student will not be able to find an answer without teacher.
• Good teacher does not provide to student any answer to student's question. Maybe because teacher is not qualified enough and thus he just does not know the answer. But he is still good teacher. Because he implicitly forces student to find answer without teacher. In the future, such student will become self-sufficient professional.
• Excellent teacher does not provide to student any answer to student's question as well. But there is one thing making him not only good but excellent teacher. In response to student's question this teacher also asks student a question. Thus, he forces student not only to become self-sufficient, but to learn a right way.