This was a great workshop, congratulations and thank you for that initiative.
The workshop started with an overview on how and why we use interfaces as well as some at lot of insight on recommended practice when using them.
The workshop portion was fantastic, Barry had selected 3 challenges of varying difficulty in order to ensure that there was something for everyone, rather than just assuming a specific level of experience. If you're not using interfaces or not sure on when you should be using them, I'd highly recommend taking part in this workshop.
Excellent workshop