Also, if you run tests, please consider also testing the "transfer step": a set of activities that should occur toward the end of the kata, where participants pair off on their own (after finishing their exercise booklets), and look for examples of sunk costs and the sunk cost fallacy in their own lives.

We have some handouts for the transfer step here: 1, 2, 3, 4, 5.

Printing instructions for the booklets are here.

We aren't quite sure how to structure the transfer step yet -- still in early testing there -- so feel free to play around, try something, and let us know how it goes. Much thanks if you do!