Offering teenagers cash to do well in their GCSEs is likely to have little impact on their results, according to research.
While parents may use financial incentives to motivate their children to get good grades, a new study indicates that doing so may well be pointless.
But the prospect of a trip or outing in return for doing well in their school work could encourage pupils struggling with maths to do better in the subject.
More than 10,000 teenagers in 63 schools studying for GCSEs in English, maths and science took part in the research project run by Bristol University and the University of Chicago, which covered two different trials.
In the first, pupils were told that they had £80 at the start of each half-term and would lose £10 if they missed a set target for attendance, the same for behaviour and £30 for classwork and homework.
For the second initiative, students were allocated eight tickets at the beginning of each half-term and promised a trip or outing if they retained 12 tickets by the end of the half-term period.
They lost one ticket each for missing the attendance and behaviour targets and three for missing the classwork and homework goals.
In each of the schemes, the rewards were based on a theory of "loss aversion" - which says that people dislike losing something more than they like gaining something.
The findings show that in the case of the cash incentives, although there was evidence of improvement in classwork, overall there was no evidence that offering pupils money had a significant positive impact on their GCSE results in any of the three subjects.
"This may suggest that even when there is a marked improvement in effort in classwork, this does not translate into higher GCSE attainment," researchers said.
There was also no impact on the students' behaviour, attendance or homework effort, they added.
The study also concluded that offering pupils the chance of a trip or outing had no overall significant impact on GCSE results.
But the maths scores of pupils who had previously had low-attainment in the subject did improve, with youngsters making two months extra progress on average, around a quarter of a grade in GCSE maths.
Dr Kevan Collins, chief executive of the Education Endowment Foundation, which published the research, said: "The use of incentives in schools is not a new idea and can appear attractive to schools and parents who are trying to motivate their children.
"The study suggests that while incentives can increase effort in the classroom, their direct impact on learning is low. "
He said it was important to evaluate schemes like these to know what does and does not make a difference to pupils' learning, especially for poorer students.
"While incentives may change surface behaviours, what really makes the difference is how students are taught," he said.
"The best evidence currently available suggests that the most powerful driver of achievement in schools is great teaching, particularly for students from low-income families."
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