## Generating the Mandelbrot Set with PearDeck

One of the benefits of being a digital packrat having a digital file cabinet is that every old file can be a starting point for something new.

In PreCalculus, I decided to do a short conic sections unit to fill the awkward two weeks between the end of the third quarter and the start of spring break. We’ve centered all of our conversations around the idea of a locus of points. I realized yesterday afternoon that the Algebra 2 activity I described here would be a great way to have some inquiry and experimentation on the day before break.

The online collaborative tools have improved considerably since 2012 when I first did this. I put much of the lesson into Google Docs and PearDeck which made sharing answers for the final reveal much easier. Here’s what the students had for values that either “escaped” or were “trapped” in the Complex Plane:

I compared this to the pixelated Mandelbrot set I hacked together in Processing from Daniel Shiffman’s code five years ago. Still works!

You can access the entire digital lesson with links as a Google Doc here.

## Math is everywhere! – fractals on the Franz Josef glacier

One of the stops on our New Zealand adventure was at the Franz Josef glacier on the West coast. We went on the full day hike which gave us plenty of time to explore the various ice formations on the glacier under the careful eye of our guide. Along the way up the glacier, I took the following series of pictures:

All of these were taken on the way up the glacier. Can you tell in what order I took them? If you’re like my students (and a few others I have shown these to), you will likely be incorrect.

I realized as I was walking that this might be because of the idea of self-similarity, a characteristic of fractals in which small parts are similar to the whole. When I showed this set of pictures to my geometry class, I then showed them a great video video zooming in on the Mandelbrot fractal to show them what this meant.

The formations in the ice and the sizes of the rocks broken off my the glacier contributed to the overall effect. Here is another shot looking down the face of the glacier in which you can see four different groups of people for a size comparison:

The cooler thing than seeing this in the first place was discovering that it’s a real phenomenon! There are some papers out there discussing the fact that the grain size distribution of glacial till (the soil, sand, and rocks broken off by the glacier) is consistent throughout a striking range of magnitudes. The following chart is from Principles of Glacier Mechanics by Roger Leb. Hooke:

In case you are interested in exploring these pictures more, here are the full size ones in the same A-B-C-D order from above:

Oh, and in case you are wondering, the correct order is B-C-A-D.