How I Use It
I have been using Code.org in my 8th grade Computer Literacy course in the last 2 years and found it to be a great way to introduce key concepts of programming to students with all levels of knowledge about programming.
I let students progress at their own pace but set a goal (stage 9 - the farmer). Once the course give them a basis in programming logic and using block programming, I have students use Google Cs-First, so they can apply the concepts making real games in Scratch.
The dashboard that tracks student progress is great, since it allows you to see which stages students did and if they were able to finish using the best solution (what teaches them efficiency in coding).
I'm a big fan of code.org - both the idea behind it and the final product they have made available. The puzzles make it a fun way for kids - and even for adults - to have a first contact with programming and the logic behind it.
I find code.org more interesting to use with kids than codeacademy, for example, because it focus on logic, and once kids understand the logic and concepts behind programming, they are able to apply them to any programming language.