It is not a ban but a guideline. The guideline says that smartphones should not be used in class unless it has an educational or medical reason. Schools themselves can decide whether they want to allow smartphones in the class or not. That said, apparently there is a huge problem with children using Snapchat, Instagram, TikTok or any other social media, and research has shown that allowing smartphones in class is a disturbance and leads to lower student performance.

My 16 yo high schooler thinks removing phones from the classroom is a great idea (southern US). According to him ithe number of students who are on their phones instead of paying attention is too high, he's even fallen into that trap. His middle school tried to have kids turn in their phones before they entered the room, several just snuck them in and a few were stolen. The school eventually gave up. In HS his teachers are so overwhelmed and under staffed they don't even try to enforce rules like this.

Similar policy in most, if not all, UK schools. Phone out in class? You’ll get it back at the end of the day in my kids’ school

As a teacher I'm no of this at all. Having the option to let the students do research on their own devices is one of the things that really helps and also is close to their day to day life. Also them having tablets for taking notes makes giving out worksheets so much easier. No longer throwing around hundreds of pages of paper per day.

Do they realy think this will stop procrastination?

Mobile phones are a disturbance, scientific research shows. We need to protect students against this.

Wish the Guardian would have looked into this at all, researched a bit to see if the data backs this up. I couldn't find much conclusive evidence of a significant impact. For example,

https://www.psychologytoday.com/us/blog/ulterior-motives/202101/cell-phones-harm-classroom-performance-bit

Is this any news to people in the US? In France there is no way you're pulling out your phone from your pocket, or your parents have to get it from the supervisor (or you can get it back yourself at the end of the day depending on the school rules)

But you have a computer at your disposition when it's relevant

Paper will soon become obsolete in the classroom and then this will look like the crazed decision of a luddite.

Already a thing in Australia (maybe not all schools)

Well, maybe you need to interest the students to get them to listen to you?