kaneton is a microkernel that has been designed for building flexible, reliable and secure operating systems.
Its design includes many modern paradigms while being written in a real-world low-level programming language: C.
This microkernel has been designed to be ported on many architectures without being intrusive. Moreover, the main goal of this system was to be understandable by everyone interested in operating systems internals.
As such, the kaneton design and implementation are very elegant and easy to understand. The kaneton microkernel includes modern distributed system concepts leading to a powerful microkernel based operating system.
More information can be found in this article submitted as part of OSNews' operating system contests in which kaneton competed.
One can find additional details about kaneton's architecture on the official website: http://kaneton.opaak.org.
kaneton has been used as the main material for last-year students in french engineering schools, most specifically EPITA, to teach operating system internals, low-level development, microprocessor theory and more.
NOTE: kaneton is no longer maintained and has been, as a result, open sourced. Feel free to use it as teaching material if you want.