My kids were basically required to have a phone for school. In theory they could use a laptop for everything but in practice it was assumed you had a phone.

They were supposed to use the calendar for assignments (and were given time to use the calendar), the teacher would tell them to take a picture of the white board with their homework assignment on it, and they used some private app (don't know the name of it) for messaging the teacher.

This was a few years ago though, so maybe now the tide has turned?

Edit: The rules have changed:

https://tea.texas.gov/taa-letters/implementation-texas-house...