Children, who are taught by good teachers, score better during their exams, says a new study.
The study, commissioned by the Sutton Trust charity, found that pupils from poor backgrounds suffer the most in lessons taught by the worst performing staff.
It also discovered that replacing a bad teacher with the most highly effective performers was worth the equivalent of an extra year's learning.
The latest study concluded that bringing the lowest-performing 10 percent of teachers up to average standards would lead to sharp improvements in our international ranking.
"Two thirds of school budgets are for the costs of teachers and the achievement of pupils is largely determined by the quality of teachers," the Telegraph quoted Sir Peter Lampl, Sutton Trust chairman, as saying.So the single most important way to improve the UK's international performance is to improve the quality of its 400,000 or so teachers.
"We believe that this can be achieved by giving teachers the right support, training and incentives and it is absolutely essential that this be carried forward," he stated.
Researchers from the London School of Economics and Stanford University in the United States reviewed a series of academic studies into the relationship between teaching performance and classroom standards.
They found that one year with a very effective teacher could add between 25 and 45 percent to an average pupil's performance in mathematics exams.
The data came from a US study that compared test scores for similar pupils subjected to varying standards of teachers.
"The effects of high quality teaching are especially large for pupils from disadvantaged backgrounds, who gain an extra year's worth of learning under very effective teachers compared to poorly performing teachers," the study concluded.