Extending Scratch: New pathways into programming

We present the Scratch extension system, a toolkit that enables anyone to extend the vocabulary of the visual Scratch programming language through custom programming blocks written in JavaScript. The extension system is designed to (i) enable innovating on the Scratch programming language itself, in addition to innovating with it through projects, and (ii) enable the creation of new interest-driven pathways into Scratch programming. In this paper, we describe some of the prior work done in this space, our design and implementation, open questions and challenges, and some preliminary outcomes.