Because this extends to the whole day, including breaks. It isn't just about concentrating on individual classes, it is also about creating a culture that isn'

Because this extends to the whole day, including breaks. It isn't just about concentrating on individual classes, it is also about creating a culture that isn't focused on and actively promoting excessive smartphone use. You cannot expect individual children to create cultural change (and thereby socially segregate themselves); such change must be a top down approach to be successful.