they motivate and inspire pupils. They explain schoolwork clearly and cogently. And they provide classroom support and guidance. In fact, a boy's mates are invaluable to his schooling, according to new research.
Traditionally the education a boy received from his mates was of the sort whispered surreptitiously in the school locker room. But Michael Irwin, from Massey University in New Zealand, believes that they also play an active part in the more formal learning process.
Mr Irwin spoke to more than 311 secondary school boys, to determine the role their friends play in helping and hindering their education.
"Mates", he found, were distinct from the more mundane "friends". Friends were people boys might hang out with. Mates, on the other hand, were trusted allies.
One boy commented: "If you don't have mates, you don't want to come to school at all. Mates are the most important part of school."
If a boy is struggling with his homework, he goes to his mates. Similarly, if two mates are having difficulty with the same topic, they try and help each other out.
Unlike teachers, mates are able to explain school topics using easily accessible vocabulary.
One of those interviewed said: "I've got a few smart friends. They usually have the answer to everything. Maybe it's because they learn the same way you do. They can explain it better because they know what you are like."
Boys might fear being laughed at or punished for their failure to understand a topic if they go to teachers for help but mates are different. As another boy commented, "If my mates get something and I don't know what the hell to do... they'll probably laugh at me, but that's just mates. They do care, and they're going to help you."
And mates do not tend to be so worried about abiding by the rules. While teachers might not produce notes for boys to copy if they miss a day of school, mates will.
But, Mr Irwin adds, it would be inaccurate to view a teenage boy's friends as a ready-made study-group, concerned only with comparing lesson notes and boosting academic performance.
More than a third of the boys questioned admitted that their mates were often a distraction in school, talking through lessons and mucking about. One boy said: "Talking about the weekend you get right into that and, next thing you know, the period's over."
But, Mr Irwin concludes, teachers should not assume that groups of teenage mates are trouble and automatically separate them in lessons.
"Mates have a more positive than negative effect on schooling," he said. "As boys develop and mature, mates keep a boy at school, assist with emotional balance and stress, and help with learning and development of knowledge."