My wife's a primary school headteacher (or K-12 as you say in the States). Her MacBook was disabled by this. Yes, she takes weekly backups, but schools don't have free money to spend on spare laptops for a few days' work, nor on unnecessary technician time to fix it. Fortunately I spotted this posting (thanks, HN poster!) on blearily checking HN this morning and instantly recognised this was what's happening.
Have some decency for the people whose lives you've just affected and apologise to them.