Use the frontmatter of a page to add it to a cursus, ie. a pedagogic path.

pedagogic_paths:
  - slug: learning-about-light
    level: 2
  - slug: understanding-virtual-reality
    level: 1

• Define the cursus via the pages' metadata
• Make sure the language selector works on cursus pages
• Display links to related cursuses at the bottom of a page
• Index cursuses somewhere