5th Encuentro Colombiano de Combinatoria
The ECCO summer school is organized every other years in Colombia. I was there to introduce Sage to the participants as part of my mission in OpenDreamKit, as you can read here: OpenDreamKit at ECCO 2016.
This was such a rewarding experience that I wrote a whole post about it. This post was then published by the AMS blog, On teaching and learning mathematics.