Saw a neat tweet from Dan Anderson earlier in the week:

Post publication note – Dan wrote to me to say that his program has an error in it and that this program from Martin Holtham has the error corrected:

Our project with Holtham’s program is here:

Using Martin Holtham’s Inversion Program

These inversions are such a fun area of geometry and one that kids hardly ever get to see, so I was really excited to play around with Dan’s program. Today I used it for a fun project with the boys.

We started with a one dimensional introduction to inversions:

The next thing I did was have the boys try out an inversion for a simple 2d shape – they took about 5 min to draw out how they thought the process would work. Here are their drawings and their explanations:

Next I introduced the boys to Dan’s program – there were lots of surprises!

At the end of the last video my younger son noticed that pentagons always seem to invert to be pentagons. That led to a fun discussion about lines, angles, and eventually circles.

So, another really fun program from Dan Anderson and a great opportunity to talk through some really interesting math with kids!