Schools that ban mobile phones and impose old-fashioned punishments such as writing lines will get full backing from Ofsted, its chief says.
Amanda Spielman believes the arguments for having phones in schools are 'dubious at best' and phones make life 'miserable' for teachers trying to deliver lessons.
She says her inspectors will 'support' all heads who refuse to let phones on school premises in a drive to improve behaviour and crack down on 'low level disruption'.
And she also wants to see schools imposing proper punishments for poor behaviour, such as litter picking or detentions, because 'there is nothing kind about letting a few pupils spoil school for everyone else.'
It comes after Culture Secretary Matt Hancock said phones should be confiscated at the start of the school day because they have a 'real impact' on academic achievement.
'While it is up to individual schools to decide rather than government, I admire head teachers who do not allow mobiles to be used during the school day,' he wrote in The Daily Telegraph.
Mrs Spielman's support for the idea is important because head teachers religiously follow the standards regulator's guidance in the belief that it will boost their inspection scores.
In her speech to the Wellington College Festival of Education, Mrs Spielman will say that pupil behaviour is the number one concern that parents and teachers raise with Ofsted.
'There's no doubt that technology has made the challenge of low-level disruption even worse, which 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,' Ofsted's chief inspector will say.
'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.' Mrs Spielman is preparing to launch a new school inspection framework in September 2019, which she wants to have a clearer focus on behaviour.
She believes poor behaviour is a 'primary driver' of low morale among teachers, who too often are not able to teach properly because of constant disruption.
'When I talk about behaviour, I'm not just talking about serious disruption or bullying, important as these are,' she will say. 'I want us to look just as hard at low-level disruption, which stops pupils learning and which can make the job of classroom management miserable.
'That is why we expect heads to put in place strong policies that support their staff in tackling poor behaviour. 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 detentions. And where they are part of a school's behaviour policy they'll have our full support.'
Her tough approach comes amid a crisis in schools over mobile phone use, with teachers regularly the subject of cruel pranks in which they are photographed and filmed in class.
Experts also say phone use among pupils is leading to 24-hour cyber-bullying.
Mrs Spielman's tough stance on discipline was criticised by Nick Brook, deputy general secretary of the National Association of Head Teachers.
'Taking a firm stance' is not the right approach in every case and school leaders need to feel confident that Ofsted will back their approach to behaviour, whatever it may be, so long as it is working,' he said.
This article has been adapted from its original source.
© Associated Newspapers Ltd.