This is not much different than the electronic ankle bracelets parolees have to wear while on "house arrest"
Man, I would have never gotten any of the log cabin forts built when I was a kid if the cops could track my truancy!
Scary stuff - there is no limit to the control the government is trying to impose. Black boxes in cars and rfid chips in every man, woman & child.
I am kind of surprised the government is letting us discuss this!
Heck, it reminds me of my last job where I had to wear an electronic co-tag to enter the building. It would open/unlock doors to the building, floors, labs, (and in some cases, elevators) but could also be used to log when I came and left work, my floor, etc. My actual office itself used a metal key (but once in there, the network administrator could see everything on my networked computer desktop).
It's good (for tracking students) but bad because it conditions them to a lifetime of such monitoring both public and private. Also, if the students are not tracked after they leave the bus (or while waiting for it), this would seem to serve protection for the school to say "the buck never got here" or "I got him/her there safely, it's out of MY hands" (C.Y.A.).