Clearing data frame projection of current mxd using ArcPy?

Question

I am required to open a bunch (50 per week) of mxd's and 'Clear' the Coordinate system from the data-frame to make sure my students have all of their data projected in the same (correct) Coordinate System, to see if their data 'lines up'.

I do this by hand, over and over and over, by using the steps below:

-Right Clicking the Data Frame

-Go to the Coordinate System Tab of 'Data Frame Properties'

-Click on the Globe dropdown arrow

-Scroll to 'Clear'

-Click 'OK' or 'Apply' as I watch to see if any of the data disappears.

There has GOT to be a way I can copy/paste a short line of Python into the Python Window to automate this. I know I could write a complete script that would check the coordinate system of each layer in the map without actually opening the map, but I'm just looking for a quick fix that I can do while I also evaluate their cartography.

I am using ArcGIS 10.2.1 for Desktop with an Advanced level license.

Answer 1

This is pieced together from the link @PolyGeo commented.

Copy/paste this into the Python window:

sr = arcpy.SpatialReference()
sr.loadFromString('{B286C06B-0879-11D2-AACA-00C04FA33C20}')
mxd = arcpy.mapping.MapDocument("CURRENT")
df = arcpy.mapping.ListDataFrames(mxd)[0]
df.spatialReference = sr
arcpy.RefreshActiveView()

I tested it in ArcMap and it works.