How old are the children in your class?
Can you give any other suggestions about other programming languages that can be used as kids grow older?
But there's now a free online tutorial system aimed at "Scratch kids" who want to take the next step. http://s2js.com -- tutors kids through the bits of Javascript they need to know in order to write graphical games that'll run on their smartdevices. It's tutorial, simple development tool, private image storage, and deployment facility all in one.
It's "Javascript as told to Scratchers", and the goal is to provide a bridge that gets them from the delights of Scratch, onto something else that will take them on their journey. S2JS isn't the destination, it's the "enthusiasm transfer tool".
Squeak has a comprehensive ecosystem; here's an excellent book for high-schoolers: http://www.apress.com/9781590594919
The complete pdf can also be downloaded from the associated website: http://rmod.lille.inria.fr/botsinc/
Now imagine this combined with hardware robots...
Also, we have started to build a Scratch Extension system, where Javascript can be used to extend the functionality of Scratch (you can define blocks that call web-apis, etc.) We will have more information about that in 2015.
After scratch we have seen some of the kids get excited about js mostly through the khan academy resources (have you tried it)? Also code combat has been a recent favorite.
Our older and more advanced coders are ok with codecademy.
Also we have some that really want to get their work out to the world, so after a while on scratch they teach themselves html and css.
We are very particular about not lecturing, not forcing a learning approach, just facilitating as different learning styles find their way.
Also if anyone is interested we are giving away our "code club kit" including resources for starting a code club. It has been the most rewarding part of my career. Just let me know and I'll send it in email.
I have literally heard kids shout out "Oh! That's why we learned those x y things in school!" when learning how to move sprites about on a grid. They have no idea they are learning math, and they generally have a spectacular time making even the simplest game, like a scrolling shooter, or moon lander.
My favorite discovery during our three years has been seeing how kids name their games. It's never "David's Moon Lander." It's always something more like "David's Super Awesome Cat Launching Space Lander With Flame Throwers." It's like watching kids draw anything they want with crayons: they get to theme and tweak games however they see fit.
As a volunteer organization, we can always use more teachers to help us spread Scratch to the masses. Our classes are free and offered to kids ages 8 to 14, and we do a simple game each week.
http://www.themade.org