Here’s an introductory video, from Scratch’s website:
Project Based Learning: Scratch can be used in all sorts of projects. First, it is itself a project – the deliverable of a “Learning to Code” project. Second, especially once students possess the necessary skills, programmed games could be fun ways to force characters within the story to provide the content of the project. For example, a character could be from a fiction story, and the game is an interactive version of the plot and its major conflicts. Students could also force characters to ‘discover’ evolution by collecting all the major pieces of evidence that led to the theory. Finally, it could be a creative outlet for their own fiction.