GPS can be useful but not for teaching basic navigation! As an instructor I often have a hand-held GPS running during a cross country navex but not where it can be looked at (either by the student or myself). After the flight is complete the track is downloaded on to a chart and forms the basis for de-briefing the flight. Then there is no debate about where we actually were and a comparison can easily be made with the planned flight.
If we have the technology we ought to take advantage of it.