I teach middle and high school PE and Health in a public school. Last year, I had the opportunity to order a set of heart rate monitors for my classes jumped at the chance. POLAR has a set designed for use in large group settings that make administering the system quite easy. Each student is assigned a watch, a monitor and strap. (The strap is a piece of elastic that attaches to the monitor and goes around the chest, and there are always clean straps available for each student). Students wear the monitors during class, while their heart rate is recorded onto the watch. Students get immediate feedback as to their heart rate and exertion level during any particular activity. Later, this data is download to a computer, for more detailed analysis. Students can see a graph of the HR data through class to identify areas of improvement. In my district, the data is used as their primary grade. If they stay in (or above) their target heart rate zone for 80% of class on a particular day, they've earned an 80% for that day. They don't get any points for being under their zone. In fact, the watch beeps like crazy when a student is out of their zone to get their attention.
This system, coupled with daily aerobic and strengthening activities has dramatically improved the fitness level of my students over the course of a year. The HR data is used by me and only me. The district doesn't seem to care about HR data at this time so I wouldn't be concerned about it being filed away for later...yet. Many districts are starting PE initiatives to get kids active, and some of that energy is going into fitness testing, where scores are tracked from yer to year. My understanding is that the scores are used in an academic sense and shouldn't be used in any medical situation. PE Teachers are not doctors so any data collected from us should not be considered by any reasonable insurance company.
In short, HR monitors are good for students, teachers and parents, when used properly.