Make the rule simple enough for a tired teacher at 3 pm. Phones off, stored on entry, returned on exit, with clear exceptions written down for medical need. The guidance now expects phone-free by default through lessons, corridors, break and lunch, so your system must cover all of it. If storage is vague, staff improvise, pupils argue, and the day turns into dozens of tiny confrontations. If storage is fixed, the argument dies, because there is nothing to negotiate. Parents want reassurance, so give them a single route: call the office, and the message gets passed. Then pupils relearn boredom, which is where friendships, games, and actual mischief are born.