Of all the strands in these materials, this is the one with the content you can find most easily find in lots of places. It's all the theoretical knowledge about music – the names of the notes, time signatures, keys, bars, slurs, ties, first time bars sort of stuff.
To avoid cluttering up the other projects and repeating key bits of knowledge, you'll find you are referred to the relevant Musiknow.
The Musiknows that are part of Learning Collection 2: Learning lots with Monteverdi's Gloria
(click on the links to download a PDF to your computer)