Opposition leader says a future Conservative government would ban phones in schools, as teachers’ union also backs social media banGeraldine McKelvie is a senior correspondent at the GuardianOne of the UK’s biggest teaching unions has called on the government to ban social media for under-16s over concerns about mental health and concentration.Teachers are dealing every day with the fallout of a social media landscape not originally designed and not suitable for children. Social media companies have shown time and again that they will not act responsibly unless they are forced to do so.If we are serious about safeguarding children, protecting