Singapore, Dec. 9 -- What is the ideal number of tuition hours a pupil should receive each week to improve his grades?

Three to four hours, it seems - or about an hour of extra classes every other day.

That is what many parents believe will be best for their children, a recent poll commissioned by The Straits Times showed.

Yet, nearly a third of pupils attend over four hours of tuition per week.

National University of Singapore economics lecturer Kelvin Seah said that taken in moderation, tuition may help to improve academic performance.

"However, it might become counterproductive if too much time is spent on it. Students might end up disliking the subject if they are forced to attend long hours of tuition on it, as fatigue and bo...