Whoa, hold on. I agree with you, but there is a difference here.
You, as owner of the computer and parent of your children, put a code in that allows you to determine and track where your property is. You have that right; well and good.
What is wrong here is that the government (i.e. school) misused their technology and spied on private citizens in their home. They may have in loco parentiis "rights" when the student is AT school, but not at home when parents are present. They likewise have no right to spy on the parents residing in that home. There are ways of determining the location of a wayward laptop without resorting to what amounts to government interference and invasion of privacy.
I would imagine that if the computers have camera capability, they also have voice capability. That’s another violation of privacy, there.