The chief inspector of schools has backed calls for mobile phones to be banned in schools.
Amanda Spielman will announce on Thursday her support for any headteachers who choose to introduce policies that forbid children from using their phones.
Speaking at the Wellington College Festival of Education, the head of Ofsted will say: “There’s no doubt that technology has made the challenge of low level disruption even worse, which the way is why I also support recent calls to back heads who have decided that the way to improve behaviour is to ban mobile phones in their schools.
“I’m not the target audience, but nevertheless I am yet to be convinced of the educational benefits of all day access to ‘Snapchat’ and the like; and the place of mobile phones in the classroom seems to me dubious at best.”
Her intervention comes after Matt Hancock, the Culture Secretary, said that children should have mobile phones confiscated at the start of the school day.
Writing in The Daily Telegraph this week, Matt Hancock suggests more head teachers should "follow the lead" of colleagues who ban phones during school hours because the devices can have a "real impact" on academic achievement.
As well as being a distraction, mobiles expose children to cyber-bullying, Mr Hancock said, as he questioned why pupils need to have phones at all.
A group of Tory MPs have written a letter backing the Daily Telegraph's Duty of Care campaign and calling for schools to ban phones because they can be a "disaster" in the classroom.
Ms Spielman will also use her speech to signal her support for schools that take a tough stance on unruly pupils, saying it is "entirely appropriate" for youngsters who misbehave to face punishments such as school community service, writing lines or detention.
"I fundamentally disagree with those who say that taking a tough stance on behaviour is unfair to children. Quite the opposite, there is nothing kind about letting a few pupils spoil school for everyone else,” she will say.
"That is why we expect heads to put in place strong policies that support their staff in tackling poor behaviour. “And I think it's entirely appropriate to use sanctions, such as writing lines, 'community service' in the school grounds - such as picking up litter, and school detentions. And where they are part of a school's behaviour policy they'll have our full support.”
The Ofsted chief will also say that the watchdog is looking at whether schools are attempting to hide naughty students from inspectors during inspections.
"I want to address once and for all, the constant rumours we hear about badly behaved children being hidden from inspectors, perhaps on conveniently timed school trips,” she will say.
"My research and analysis teams are currently designing a study to assess the extent of the problem, and what we might do about it."
A Department for Education spokesperson said: "Head teachers already, of course, have the power to ban mobile phones in schools and we support their right to do so. "We know that 95% of schools already impose some kind of restriction on mobile phones use during the school day, with a substantial number banning them from the school premises altogether."