There is a negative correlation between homework and achievement in science. According to findings from the Programme for International Student Assessment (Pisa), published last month, students from countries in which less time is spent on private study at home or being tutored tend to do better in science.

In the UK, students spend 17 hours in total studying outside school each week and achieved a mean score of 509 in science. In comparison, pupils in Japan spend 13.6 hours studying after school and achieved a score of 538 - the second-highest total after Singapore.

In countries with the poorest Pisa scores in science, such as the Dominican Republic and United Arab Emirates, students spend 25 and 29.7 hours respectively learning outside the classroom every week.

There are outliers: students in Singapore, where a lot of time is spent preparing for exams after school, achieve a Pisa score of 556 in science and spend a total of 22.2 hours per week learning outside the classroom. Compare that with Finland, where pupils spend less than 12 hours a week outside school on their studies and achieved an average score of 531 in science.