While it is possible to use a GPS sensor with a desktop or
laptop system, the integration of location services in a mo-
bile device is much more engaging, and exposes the student
to real-world issues of sensor data reliability and permanent
storage. In addition to the actual device location returned
by the hardware abstraction layer, we also ask students to
store the relative age" of the location data (the number of
seconds since the location was last updated in the kernel).
This provides a basic condence metric that can be used
when later retrieving a le's location.