Applied CS Skills is a free online course by Google which teaches CS skills. The course consists of twelve lessons which each comprise a teaching/preparation section and a workshop which guides the students as they create code to solve algorithmic problems involving core CS concepts such as stacks, binary trees and graphs.
I wrote and launched the initial site which required sudent registration and was built on top of Google's open-source Course Builder platform, and rand from 2017 to 2019. I then converted the site to a fully static "evergreen" site without registration, which launched in 2020.