The switching chamber for a heavy-duty circuit breaker which can be filled with a quenching gas has a first arcing contact piece and a second arcing contact piece, of which at least one can be moved by means of a drive. The frame assembly includes a pair of tapered members attached to opposing sides of a backrest sofa part and a pair of receptacles attached to a respective one of a pair of rails, which are in turn attached to a pair of armrests. Although particularly well-suited for tracking attendance in schools, the present invention can also be used in a variety of other settings where there is a need to track the whereabouts of a number of individuals. The first triggering element is disposed above the first tilt sensor.