Sherlock is smart, at least smarter than his friends, though he didn't have many. During exams people always try to get him to tell them the answers to the questions but he doesn't often give in

During their last science exam, Sherlock was writing some answers in his paper when he got a hushed call from his friend asking him for help

"I'm not gonna give you the answer, you should've studied”

Sherlock answers back, in a whisper as to not be heard by the teacher