Opening windows would be 'much more effective' at cutting the spread of Covid in schools than getting children to wear face masks, one of No10's scientific advisers claimed today. SAGE member Professor Calum Semple said he is 'not a fan' of asking young children to wear masks and insisted there are better strategies for managing the virus. Ministers yesterday confirmed that face coverings would not be made compulsory in primary schools. But some schools have already defied the official guidance and insisted youngsters as young as five must wear coverings when they return to the classroom on March 8, in the first step of Boris Johnson's roadmap to freedom.