Beyond that, I'm sure there's a litany of PII in the office for the students.
This is one thing, at least in the states, that really chaps my rear. My dad is the lead network engineer for the school district in my hometown. He basically had to beg on his knees to get them to provide the budget for adding extra network security (because they basically had none). I'm talking basic components like IPS licensing for their firewall and inbound internet proxying. And that was from the state level, not local.
Seems that security of student information is almost an afterthought, but gathering their data would be a super lucrative criminal venture. I'd wager 70% of public school systems out there could have a full data breach and never know.