A School CTF event.
Official URL: http://school-ctf.org/
School CTF is the computer security competition for school pupils that is hosted by the SiBears team annually since 2010. School CTF traditionally takes place in autumn, but in 2014 School CTF was postponed to the spring semester. Any team is welcome, not just that comprised of school pupils. The ratings are calculated separately for school teams and for all teams.
Participants, note that the actual URL is http://school-ctf.org/. There is a note at http://blackbox.sibears.org/ about this also.