Greater emphasis should be placed on helping teachers to become better at their jobs, rather than attempting to cut class sizes, it has been argued.
According to the deputy director of the London-based Institute of Technology, Professor Dylan William, pupils taught by the best teachers are likely to learn four times faster than those who are taught by poor or mediocre ones.
Given this, a policy of using 'formative assessment' to get regular feedback on teachers' performance with the aim of improving standards could deliver far more effective results than attempting to reduce class numbers from 30 to 20 students.
"A focus on formative assessment can generate as much as eight extra months of learning per year at a cost of only £2,000 per classroom," the professor is expected to tell an Institute of Fiscal Studies conference.
"This is around 20 times as cost-effective as class-size reduction."
Should the government go ahead with plans to reduce class sizes, it is estimated that a further 150,000 teaching jobs
will be created, with the cost likely to come to around £20,000 per classroom.