On enabling children to use Internet services in a meaningful way, and a discussion of the benefits:
miniblog.
Related Posts
Writing an IRC server, exploring object systems, and enabling hot reloading for clients: https://technomancy.us/197 (in Lua and Fennel)
The Shelf is a NeXTSTEP alternative to a clipboard, but more flexible and powerful: https://en.wikipedia.org/wiki/Shelf_(computing)
You can put a source file and destination directory on the shelf, enabling a cut-and-paste style operation. You can still refer back to them afterwards!
Adding differentiation as a first class concept in Swift, enabling stepping through ML code and type safety: