In my current job (ulabox) we do every Thursday a internal training session, usually prepared by one of our department members. Some months ago I prepared a code kata on design patterns, with 5 steps with instructions. The idea was to push the team to debate about different approaches to a common problem, and show them some classical design patterns, as a way to polish our weapons. The result was good, but the discussion only really happened at the end, when I showed them those patterns.
Some weeks later I heard about a code conference in Barcelona, organized by the Barcelona Software Craftsmanship group, so I took the chance to polish my kata and ask them to do in the event. It was rejected to the main event.
Later I heard about Monday’s katas: this group organizes every Monday a code kata with up to 20 developers. I offered my kata and our office to do it, and on December 12th we did it! All participants agree: the kata is smooth and induces to think about the subjects it later shows.
I published my kata on github. Have fun!