Note from future Dan: I haven't worked on this in years now, this was from when I was an Apprentice.
Calcium is a School VLC/CMS with a IT Helpdesk. It has seen development from a small number of people. Currently, I'm responsible for Calcium's Dark Mode, a feature I had initially requested and ended up being in charge of it.
There are plans to give Calcium additional features, with the current roadmap including a redesign, a major CSS cleanup, colour templating and more admin focused features.
The link to the stable repository is https://github.com/Poole-High-School/Calcium.
I currently have a tiny role in Calcium's development, with nearly all the current development being done by the lead developer Madison Spry. (@m_spry / http://mspry.net).