We are developing a student-monitoring system, but I foresee one potential problem: If a student were to bring his or her friend's tag to school, both tags would be read and it would appear that both students were in attendance. How could we identify any students carrying more than one tag into a classroom?
I believe that most schools address this issue by informing students upfront that there will be significant penalties for anyone caught bringing a classmate's tag into a room with them, switching tags and so forth. Often, schools suspend children for several days if they try to do this.
One easy solution would be to erect a small display showing the number of tag reads. Teachers could then conduct a head count and confirm that the number of tags detected matched the number of bodies present. If there were too many tags, the instructor could try to figure out who might have two, or at least identify whose tag was interrogated despite that person not being present.
If you wish to implement a surefire technology answer to the issue, one possibility would be to use video and link it to the RFID reads. If video analytics showed that only one person passed through a doorway at a time when two tags were interrogated, an alert would be sounded and you could investigate whether that student had two tags.
You could also use infrared heat sensors. However, this would greatly increase the system's cost and complexity. In addition to deploying readers at every classroom door, you would now have to install video cameras or heat sensors. These would need to be linked to a high-powered computer that could perform real-time video analytics, and also to the RFID system so that the video could be compared to the leads.
Personally, I'd go with performing head counts and implementing a policy of suspending students who break the rules.
—Mark Roberti, Founder and Editor, RFID Journal