A passive tracking device, a processor configured to receive information from the tracking device, and a database accessible by the processor, among other elements, are disclosed. A first activity unit having a first start time corresponding to detection of engagement is monitored. The processor is further configured to establish a first end time of the first activity unit using the monitored information, and automatically ascribe a classification of the first activity unit. The classification of the first activity unit is output to a display of a computing device, and the classification of the first activity unit is stored in the database. A revised classification is output to a display of a computing device, the revised classification is stored in the database.