In a word DONT! Do what my kids school does - if you are found with your phone on in school it is taken off you for a week.
This is a terrible idea, and I can't believe your kids school does that. It is just asking to get the school/district into trouble
schools are given too much power in some aspects these days, and being able to take a $600+ device from a student for a WEEK should constitute theft regardless of the reasons.
If a student refuses to stop using their phone, then send them out of class, to the principal/assistant principal/etc.
in a worse case scenario, take the phone away and require the students parent to come pick it up, so you know for sure they are aware of the issue. But still, the student should be given chances to stop using the phone before it is taken away, and again NOT for a week.
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My wife has this battle with her COLLEGE students that she teaches. It's not so much that they have and use them, it's more that they have and use them during class then get lost and need HER to stay after and "catch them up". And it's not just phones. It's browsing facebook and other social media during class.
After hearing her talk, I'm with the person above. Don't try to incorporate it. Get more strict on it. I had a cell phone in High school and it stayed in my car all day. I'm probably smarter thanthe majority of students coming out of High School today and I never had my phone in class with me. As of now, phones in classes are more of a distraction than anything.
when you're a college professor, you should be expected to be accessible to students for questions outside of class. not necessarily after class, but at my school (and most schools) professors are required to hold office hours for students who choose to come in for extra help. There are more reasons to need extra help outside of class than being on phones in class all the time.
What she should do is make it clear that she has set office hours for them to come get help, and if they miss things because they are on electronic devices, then they have only those times to get caught up (time that is shared by everyone in the class). Outside of that, she makes no guarantees on what she can do to help them.