Analyzing Coordinates Before Mapping Them

[JosephKerski]

Today’s GPS and GIS technologies allow us to quickly collect data in the field, and then quickly map the data in a GIS environment to analyze spatial patterns that the field data reveals. However, just as the ease of digital photography has allowed us to get into and out of the field rapidly, it is often advantageous for us as educators and students to slow down! Numerous teachable moments arise even before data is mapped. Consider the following points that I collected during a recent GIS-GPS workshop for educators in Colorado Springs:

point, lat, long
1, 38.98701, -104.76221
2, 38.98700, -104.76198
3, 38.98701, -104.76176
4, 38.98703, -104.76154
5, 38.98702, -104.76127
6, 38.98702, -104.76103
7, 38.98701, -104.76068
8, 38.98719, -104.76059
9, 38.98739, -104.76059
10, 38.98761, -104.76064
11, 38.98764, -104.76084
12, 38.98763, -104.76103
13, 38.98765, -104.76124
14, 38.98768, -104.76149

Observing how the latitude remained relatively constant while the longitude decreased for the first 7 points, how the latitude increased but the longitude remained relatively constant from points 7 through 10, and how the latitude remained constant and the longitude increased for points 10 through 14. From these points, can students visualize that I must have first walked due east, then due north, and then due west? If not, help them visualize this by starting with paper, pencil, and the Cartesian Coordinate System, and then entering and mapping selected points using the Esri EdCommunity latitude-longitude finder, ArcGIS Explorer Online, or ArcGIS Explorer Desktop. In addition, can they visualize based on the coordinates that the area traversed is not that large?

Once the students can start to visualize their world as x and y coordinates, then map the data, as I did in ArcGIS Explorer. Did the coordinates map where they had predicted they would be?

I am continually amazed at how accurate even recreational-grade GPS positions can be. Using the measure tool in ArcGIS Explorer, I discovered that the trees I was mapping were between 1 and 5 meters off from their location as indicated by the Bing satellite image.

Try this technique with your students and let the GIS education community know what you discover!

- Joseph Kerski, Esri Education Manager