The Hour of Code is a global movement, "a one-hour introduction to computer science, designed to demystify code and show that anybody can learn the basics." We have Makey-Makeys and Arduinos and circuit boards and banana pianos and all sorts of wonderful things, so Sean's Computer Science class hosted the event during one of our tutorial periods (school-wide free blocks) and we had an excellent turnout.
The students set up stations where interested classmates could learn about various technologies: Makey-Makeys, Arduinos, and other web applications.
Of course, the banana piano was wildly popular:
A couple of students even modified the banana piano so they could play Flappy Bird--or Slappy Bird, as it involved into:
And that, obviously, was fun for everyone.