Across the country, the problem with phones is very apparent in an educational environment. As a teacher myself, I also feel the side effects of the phone issue that seems to be much bigger than it was even when I was at school 10 years ago.
Research has shown that the use of phones in a school environment has a negative impact on pupils' performance in school and in France, there is now a law that bans the use of cell phones in schools.
Smartphones have become so feature-rich that the use of phones is no longer just for sending texts or making phone calls, or even for listening to music, but also for other things such as browsing the web, chatting on instant messaging and more. From a teachers' point of view I see smartphones as one of the worst disruptions in the classroom, but also being a teacher of Computer Science I also see them as a valuable asset for certain lessons. The balance to allow children to use them whenever I want them to, however, is impossible to get right. Pupils generally assume that when you have permitted the use of smartphones for one part of the lesson it is okay to continue to use them throughout the lesson.
There aren't many feasible solutions to this problem that do not involve blocking the signals of these phones. Since blocking phone signals is technically not a legal solution, and since one Florida science teacher got suspended for attempting it, it's certainly not a feasible solution. The other issue with blocking is the range of the blocker. If it extends beyond the classroom it is intended for it might interfere with other devices.
The next solution is to have everyone put their phones on their desks. This in itself poses a huge issue in that pupils are more tempted to access their phones.
The next solution is to allow pupils to periodically use their phones in class. But again, this can be time consuming and difficult to control. However, it gives pupils more motivation to work if they are given a reward of being able to use their phones for a minute within the class.
My final suggestion is my favourite but the most difficult to implement. All pupils put their phones in a numbered box at the front of the classroom. I was planning on implementing this but couldn't find a viable container with 20 slots that worked for modern smartphones since smartphones these days such as the iPhone XS Max are rather large.