What makes mobile phone is forbidden to be brought at school? (exposition text)

this is the example of exposition text:

Mobile phone is one of modern communication device, it seems that every single one uses it everytime. No wonder if all of people over the world do need this modern phone. Mobilephone is the important thing which always we bring anywhere, anywhen, and anytime. For examples, we use it at the office, market,  or perhaps school.

School is one of place where people often bring their phone there. Unfortunetly, most of schools do not allow their students to bring mobilephone because they think mobilephone can disturb students to study. Yet, I do not think that is the true statement.

How can I say it? Absolutely I have some reasons. First, students exactly need phone in order to communicate each others. Examples, students gotta call their parents/ somebody else for picking them up or bring something left at their home.

Second, students can find some infoemations and knowledges in the internet via mobilephone. If they have some obstacles while they are studying, they can “search” in the internet via mobilephone.

Because of those reasons, I don’t think mobile phone can disturb students to study. But they have to use their phone when the break times or after school, so that it doesn’t disturb time for study.