For example, the value of pie is 3.1415926. Mark Clear, England. I was given a Study Skills book by my parents that says you should study for 40 - 50 minutes and then take a break. Eithne Coyne, Dublin. Well Eithne, there is no hard and fast rule.
Every student is different.
With the supervised study after school, you should still break up your study into short sessions. For a break, you could read three pages of a novel and then study a different subject. The little breaks are an essensial part of the study program - without them you will quickly find you are daydreaming and getting very little done. Your organisation came to our school and gave us a seminar in March. I got an A in history - unbelievable for me.