Parents and teachers who despair about children not studying ought not to give up nagging them about how short-term pain brings long-term gain.
"If you think you have no impact, stick with it because you do," said Sydney University researcher Andrew Martin. "At all stages of secondary school, teachers and parents have a significant impact."
Martin said his study of 3,450 pupils at Australian high schools dispelled the notion that the gang the child hangs around with has more influence than teachers or parents.
The study looked at motivation, engagement, homework completion rates, happiness at school, attendance records and educational aspirations. It was published in Teachers College Record, a US journal.
"Parents and teachers who might feel powerless during adolescence have a bigger influence on academic motivation than they think - sometimes up to three times the impact of peers," Martin said.
However, when it comes to social and emotional well-being, peers have a bigger impact than parents or teachers.
A child might be doing well at school, but might not be all that happy at school. The former is likely to reflect the influence of parents and teachers while the latter is likely to reflect the influence of peers.