This website teaches computer programming. This skill is very useful: with programming you can automate computer tasks, make art and music, interpret and analyze survey results, build tools for other people, create custom websites, write games, examine genetic data, connect people with each other, and the list goes on and on.
There was some discussion at the CEMC conference about coding guidelines. I found this excellent article about the topic of Reading Code and best practices. I plan to use this in my senior (ICS4U) course early to set the standards and probably a simplified version after a few months in ICS3U.