‘In the all-girls’ class, you didn’t have to have that much courage to go to the blackboard and answer the question.’

The academics who carried out the study warned that girls who show less confidence in the classroom may be less competitive in the job market.
Dr Nolen, of the university’s department of economics, said: ‘I would like to see policy makers think about this. We should be investigating it and intervening pre-market in the environment in which students learn.’

His summary of the project in the New Economic Journal concluded: ‘This finding is relevant to the policy debate on whether or not single-sex classes within co-ed schools could be a useful way forward.’