Legacy Code Workshop
I had a great time. I learned a lot about TDD, as well as C and C++ from your examples. (I am not a C or C++ programmer)
How to improve:
I thought the legacy code workshop using our own code was great. However, I would recommend using your own an existing example of how to apply TDD to legacy code in order to keep everyone focused and speed up the delivery of the concept.
Then use the customer's code so that they have already had an example.