KidneyOS is a toy OS written in Rust, designed for teaching operating systems concepts. It is loosely based on PintOS (the name "KidneyOS" refers to kidney beans, and is a joke about how PintOS can be read as "pintos", another kind of bean). It is still a work in progress, and is not yet ready for use. If you're interested in using KidneyOS for teaching when it's ready, you can "watch" the repository for releases on GitHub.
KidneyOS is being developed by students at the University of Toronto. The project is supervised by Professor Jack Sun.
Detailed documentation for KidneyOS (including building instructions and assignment descriptions) is available here.