What is the ruling on a teacher hitting a student?

It is permissible for a teacher to strike a student for the purpose of discipline and to compel him to learn, provided certain conditions are met: the striking must be customary and not harmful, it must be with the hand and not a stick, and it must not exceed ten strokes. Furthermore, it is a condition that it be with the guardian's permission, or that striking be a recognized custom, and that the child comprehend the discipline.