To get this trophy you'll need to have a knowledge rating of at least 4 which requires at least 150 points to be earned in Knowledge increasing events. School ends in July and at that point you are given an end of term exam - this is the easiest time to get this trophy since the final exams of the game require a 5 which takes a very long time to acquire.
* First and foremost make sure that any time you are asked a question in school you get the answer right. This provides a free 3 point increase to Knowledge with no effort on your part.
* Secondly, buy the book Expert Study Methods, available from 4/20 onwards, and then get to studying. Each time you study you earn +3 to your Knowledge and this book adds an additional +3 to that.
* When tests are near talking to your S.Link's may prompt them to ask you to help them study in the library. This provides a +3 (+3 extra if you read Expert Study Methods) as well as increasing your S.Link with that person.
All that's left is simply to study your behind off. It'll take roughly 25 nights of studying to earn this, less for each answer you get right when asked in school. If you wait until you've read Expert Study Methods before devoting your afternoons to studying with friends and nights to studying in your room you should be able to get to a Knowledge rating of 4 in the week leading up until tests when nobody wants to hang out anyways. Just be sure to get the answers to those questions and you'll be fine.