Now that it is easy to gather tracks and waypoints on a smartphone and map them in a GIS, it provides a good opportunity to remind students about the importance of being critical of and paying attention to data. I recently went on a walk around a local reservoir and used the Motion X GPS app on my iPhone to collect my track and a few waypoints. I emailed the data to myself and added the GPX file to ArcGIS Online so I could map and examine the track. I made my results public and made it visible to feature some teachable moments:  http://blogs.esri.com/esri/gisedcom/2012/07/18/using-a-smartphone-and-arcgis-online-to-teach-accuracy-precision-gps-and-critical-thinking/