Why teenage pupils should wear masks in class

Last week the Department for Education (DfE) issued guidance for the safe reopening of schools. Along with regular self-testing for secondary-school children, many must wear masks. https://www.dailymail.co.uk/health/article-9333289/Why-teenage-pupils-wear-masks-class.html?ns_mchannel=rss&ns_campaign=1490&ito=1490