I've recently learned my daughter, with teacher permission, regularly has to use her phone (in her otherwise phone-free school) to get around blocks on basic stuff. Like in her math class the teacher regularly has them review techniques using YouTube videos (from an approved channel), but YouTube gets blocked every so often. Why? Very possibly no one knows. So she'll be sent to the front office where they can unlock her phone and she can use it to keep doing her work. It also came up recently when she was researching drug addiction for a paper, and all related search terms were banned.