CodeHS

CodeHS was founded in 2012 by Jeremy Keeshin and Zach Galant, both Stanford University Computer Science graduates. Keeshin and Galant based CodeHS on their experience as section leaders and teaching assistants for several of Stanford's introductory computer science courses.[3] The company joined the Imagine K12 incubator's third class, launching in October 2012,[4] and its investors include NewSchools Venture Fund, Seven Peaks Ventures, Kapor Capital, Learn Capital, Imagine K12, Marc Bell Ventures, and Lighter Capital.[5] In total, CodeHS has raised $2.9 million as of December 2016.

The first learning module on CodeHS teaches introductory programming concepts by having students give basic commands to Karel the Dog using Karel-specific JavaScript commands.[10] This approach is based on the original Karel programming language developed by Richard E. Pattis and is used in Stanford University's introductory computer science classes. Karel initially knows only a few basic commands: move(); to have Karel move one spot forward, turnLeft(); to have Karel turn left, putBall(); to have Karel put down one tennis ball in the current spot, and takeBall(); to have Karel pick up one tennis ball from the current spot. Karel can be "taught" additional commands by defining new functions composed of these basic commands. The programmer can also use elements like loops and conditionals to control the flow of the program.

After Karel the dog, Tracy the turtle was introduced.

Example

The following is an example of a simple program to have Karel repeat a series of commands (put down a tennis ball, move, turn left, move, then turn right) three times:

Demonstration of Karel the Dog executing the sample program.

<nowiki/>
  function start() {
      for (var i = 0; i < 3; i++) {
          putBall();
          move();
          turnLeft();
          move();
          turnRight();
      }
  }
  
  function turnRight() {
      turnLeft();
      turnLeft();
      turnLeft();
  }

CodeHS received significant media coverage upon its launch, including articles in the Forbes, TechCrunch, and Education Week.[11][12][13][14] The site has also been featured on various blogs for its interactive and beginner-focused approach to teaching programming.[15]

• CodeHS
• CodeHS Blog