Headteachers across the UK should ban mobile phones in the classroom, the culture secretary has said.
Matt Hancock praised those who do not allow the devices during school hours, and said more heads show "follow their lead".
He warned that mobiles could have a "real impact" on students' achievements, and linked social media with bullying among schoolchildren.
Writing in the Daily Telegraph, Hancock questioned why young children needed phones at school in the first place, and said: "There are a number of schools across the country that simply don't allow them.
"While it is up to individual schools to decide rather than government, I admire headteachers who do not allow mobiles to be used during the school day. I encourage more schools to follow their lead."
Mr Hancock added that there was evidence to suggest that banning phones in schools worked, and said "setting boundaries" was important.
He acknowledged the role of parents in teaching youngsters to use technology safely, but said schools should also play a big part.
Meanwhile, a group of Tory MPs has also urged a ban on mobiles during the school day, saying there is evidence that such a restriction can have "a beneficial effect on pupils' ability to learn".
In a letter to the Telegraph, the seven politicians, citing a 2015 study by the London School of Economics, write: "Where schools banned smartphones from the premises, or required them to be handed in at the start of the day, pupils' chances of getting five good GCSEs increased by an average of 2 per cent.
"The improvement was even more marked for lower-achieving pupils. Results among pupils in the bottom quarter of achievement improved twice as much as the average."
The group, which includes Harborough MP Neil O'Brien and Chichester MP Gillian Keegan, urges the Department for Education to give guidance to schools about the evidence on attainment.
In France, mobile phones will be banned from primary, junior and middle schools from September 2018.
A snap poll by Tes in December 2017 found that 69 per cent of UK teachers believed that schools in England should ban mobile phones.
But others disagree. Bernard Trafford, a former chair of Headmasters' and Headmistresses' Conference, writing in Tes, said that life was too short to set rules in schools that cannot be enforced.
A DfE spokesperson said: "Headteachers already, of course, have the power to ban mobile phones in schools and we support their right to do so.
"We know that 95 per cent 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."