Processing
From
Possible complement/alternative to BYOB for computational thinking strand of course.
Pros:
- Visual
- Translates well to CC/Java
- Iteration/recursion are very natural and visual in this environment
- "Real" code
Cons:
- "Real" code
- Debugging not well supported
Resources:
Main site: http://processing.org/
Javascript port: http://processingjs.org/
Online sketchpad for processingjs: http://sketchpad.cc/
Book (not free but lots of free examples/resources): http://www.learningprocessing.com/downloads/