For many years Moodle had a quirk that allowed activities or resources to be hidden inside extra Weeks or Topics, but still accessible to students…
These were known as orphaned items, and allowed Moodle teachers to achieve particular design options for their courses using this unintended behaviour.
Now in Moodle 3.3 you can set any activity or resource into stealth mode to achieve this same effect in a more officially-supported and non-hackish way.
Firstly site administrators need to enable this new function from Advanced features. Teachers will then be able to make activities or resources available to students, but not shown on the course page. This feature is supported in the standard Weeks, Topics, and Social course formats ,and on the front page. But note that other plugin course formats may not support it (although they may add this in updates).
It’s still possible to use the old method, and to create Weeks or Topics that are hidden, with links to the contained activities and resources elsewhere.
The big advantage of the new method is that it’s easy and more logical for teachers and course designers to create hidden items ‘right where they are’ within the course design, rather than in a separate location elsewhere 🙂