allow user to track course progress

I've used Articulate Studio products but just getting oriented to Storyline by watching a few of the examples in the community showcase and doing the tutorials.  There are a couple of examples that seem to allow the learner to track their own progress through the course.  I really like the idea of that!  In the Recycling course (in the showcase), a smiley face appears after the learner completes a section of the course, for example.  I'm curious how this is done; is it through use of variables?  There must be some nesting going on somehow because in the Recycling course there are subsections within sections under one overarching button and it seems like you must click through each and every subsection to get the smiley face for everything under that button.  I can't quite get my head around this yet.  Similarly, I also like the example (Ender's collection) where you have to find the articulate smiley figures throughout the course to access a 'special section'.  Can anyone point me in the right direction for getting a better understanding of this?  Thanks!