BYOB

This is an advanced offshoot of Scratch and a visual programming language primarily for kids from the Lifelong Kindergarten Group at the MIT Media Lab.

The 3.1.1 version of BYOB (Build Your Own Blocks) is an attempt to extend the brilliant accessibility of Scratch to somewhat older users—in particular, non-CS-major computer science students—without becoming inaccessible to its original audience.
In addition, BYOB features first class lists, sprites and procedures, as well as custom blocks and recursion.