In yesterday’s workshop we had a projection demonstration. We took an inexpensive inflatable globe, drew a couple of secant lines, cut open the inflated globe from the poles to the secant lines, and flattened it.
You can discuss how the areas above and below the secant lines would have to be stretched if you don’t want a disconnected projection, or you could keep them disconnected but sacrifice continuity. This is also a great visual for discussing the six things that will be either compromised or preserved in various projections: area, distance, direction, shape, bearing, scale.
Notes on the demo: You might want to have a volunteer do the cutting to make things more fun. The globe was $7.00 so this could get to be too expensive if you were doing it all the time. You might just get two inflatable globes and show the cut-up one next to the inflated, in-tact, one instead of buying a new one for every demo (though that isn’t quite as fun for the students.)
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