teacher here. phones are killing the work we're doing in schools. if you have a group of 20 and one gets a phone notification they shut their attention off for at least 3 minutes. each of those 20 gets at least 10 notifications each class. i usually collect the phones at the start of class in a basket but a lot of teachers i work with have the phone walls. sometimes its not even that they have the phones on and scrolling through them its just even having it near them in their view makes them less present and a ton more distracted.