Does striking students affect one’s fast, and does it entail sin, knowing that it causes no wounds and leads to an improvement in their academic performance?

It is permissible to hit female students for discipline and to encourage them to perform their duties. The hitting must be light and not exceed ten lashes, except within the bounds set by Allah. The teacher must balance encouragement (targhib) and deterrence (tarhib) to achieve the student's best interest.