What types students are you mentoring? I've observed that groups of the best-performing students look down on those "addicted" to their phones and some have switched to flip phones.
Sounds like a good idea though :)
if the idea of having a flip phone is so that you will be less distracted then maybe a flip case might help to do something similar. preferably one that has really loud velcro so that people around you will get pissed if you keeping opening it every 2nd minute to look at facecheck
There really is not much choice when it comes to flip phones today: https://www.gsmarena.com/results.php3?nCPUCoresMin=2&nRamMin...
Out of those only Gionee W909 has at least somewhat respectable specs.
https://www.bestbuy.com/site/nokia-3310-3g-cell-phone-unlock...