In February, Brittan Elementary School in Sutter, Calif., decided to try badges with radio-frequency identification tags for taking attendance. A few parents, with the help of the American Civil Liberties Union of Northern California, complained that they had not been informed about the tracking, that it was demeaning and that the badges might unwittingly reveal data on children's whereabouts to anyone with a reader nearby. A week later, the school dropped the idea. Earnie Graham, the school's principal, continues to argue that the devices are harmless and secure. If a person did have a surreptitious tag reader, he said, ''They could get a 17-digit number. That's all.''
In Boston, where Global Positioning System devices have been proposed for the public-school buses, union representatives have protested, calling G.P.S. a tool for spying, not safety.
Ronald Stephens, executive director of the National School Safety Center, an advocacy group in Westlake Village, Calif., said he could understand the anxiety over monitoring. ''I have to drive through an intersection with four cameras every day, and I really don't like it very much,'' he said.
Mr. Stephens said cameras were only one tool, and not always the best. ''Our research has found that the most effective strategy is the physical presence of a responsible adult in the immediate vicinity.''
Jim Newett, the principal at Ellsworth Middle School, near Bangor, Me., tried his own version of video surveillance in 2004 when he became fed up with students' disruptive behavior in the cafeteria. He brought a camera from home and installed it himself.
''It went over like a lead balloon,'' he said. ''I think the feeling was that at the middle-school level we should be able to monitor the students ourselves.''
So he assigned a second adult to the lunchroom. ''With two adults, it is a smoother operation,'' he said.
But at Ellsworth High School, a rash of bomb threats scribbled in a bathroom prompted the installation of cameras outside the bathroom, ''so we can see comings and goings,'' said Carl Stecher, technology coordinator for the Ellsworth School Department. The suspected perpetrators were identified, Mr. Stecher said, ''and the bomb threats have pretty much stopped.'' Software That Lets Teachers Take a Peek
If a software program allows a teacher to see when students start their online assignments, how many minutes they spend on an exam question and what resources they use, is that ''snoopervision'' or an eye-opening way for teachers to better tailor instruction for their students?
''It's a wake-up moment,'' said Lucinda Sanders, a technology resource teacher for the Fayette County Public Schools in Lexington, Ky. She works with Interactive Multimedia Exercises, known as Immex, an advanced instructional software program that tracks movements. Ms. Sanders has found that students, for example, were spending an hour looking up terms that she had thought they already knew.
The program, which was developed at the University of California, Los Angeles, can display what it calls a ''search path,'' a webbed diagram of the information sources that students clicked on to arrive at an answer. By analyzing the path, instructors have been known to spot instances of students' blindly guessing -- or cheating.
Other software programs combine computerized grade books, lesson plans, online assignments and logs that show how long online assignments were opened.
Jessie Woolley-Wilson, executive vice president of the education and training group at LeapFrog, the maker of one such program, LeapTrack, said the software allows teachers to say: ''Johnny, you spent only seven minutes on this assessment when you should have spent 45 minutes. No wonder you didn't get a high score.''