This is such a tough issue and I hope others pipe in with more insight. It is awesome that you are in a position to make a difference and that you want to.
Here are my thoughts:
You can do better than these platforms and I'm glad you're trying to, but a combination of your own system and use of these good tools seems like the goldilocks zone if possible.
CS is different from coding and if possible, provide a quick path to making something fun that kids can show off to each other. To this end, I think a curriculum centered around an achievable project that can be extended and built upon if kids want to hustle is ideal.
With that in mind, I would center the curriculum around JavaScript because every browser is also a JavaScript editor. It will speed things up and limit dependency frustration.
That doesn't really explain how to teach the teachers though. I'd come up with a simple project-based curriculum, teach the teachers how to get kids from a to b in that defined project structure and provide them with an instruction to, themselves, work through a JavaScript-based tutorial that goes a bit deeper into the fundamentals and environment.
CS is great, but getting kids excited about code is the key IMO. From there I'd go into some of the deeper concepts through story telling.
e.g.
This is how Google became so big and magnificent... with computer science!
This is how Alan Turing won the war... with computer science! (Bonus, you could show that wonderful movie)
This is how we put a man on the moon... with computer science (Same bonus of movies!)
This is such a tough issue and I hope others pipe in with more insight. It is awesome that you are in a position to make a difference and that you want to.
Here are my thoughts:
That doesn't really explain how to teach the teachers though. I'd come up with a simple project-based curriculum, teach the teachers how to get kids from a to b in that defined project structure and provide them with an instruction to, themselves, work through a JavaScript-based tutorial that goes a bit deeper into the fundamentals and environment.
CS is great, but getting kids excited about code is the key IMO. From there I'd go into some of the deeper concepts through story telling.
e.g.
As far as the goldilocks zone goes, do you know any code editors for chromebooks? We only have access to those.
There are some online IDE's that I've used before and are pretty nice like Cloud9!!