BYOD means just that here - the parents purchase the device and the kids take it to school: problems are usually damage or theft of the device or accessing inappropriate things in class/playing instead of working.

Differentiated task demands can be good depending on the teacher. It is not more interesting or challenging to add an extra 5 numbers to long division or to write a longer report about the same low level book. As others pointed out to it makes grades a bit dodgy.