What is a effective and interactive exercise to demonstrate cognition to a class I'm new to this site so I may mess up here and there with the question process.

I need to come up with an interactive exercise for a class to demonstrate cognition. The problem is, I find cognition to be very complex and I have trouble thinking of one.

Some ideas I currently have in mind are:

1) Telling the class some false facts or showing them some fake news and having them debate which is real.

2) Something along the lines of a slot machine where extravagant sounds and lights play when you win something, however, nothing happens when you lose. Showing how we are more likely to remember the extravagant sounds/lights.

3) Asking the class to describe to me an object. Then ask the class to describe the same object to me without the use of certain words and concepts. 

I am very clueless on this matter (cognition) so any help would be appreciated.
I would recommend something like the Invisible Gorilla! This is a classic demonstration from Simons &amp; Chabris (1999) that demonstrates the selectivity of attention. Demonstrating "cognition" is a bit broad, but this is a famous example of the ways in which cognitive processes select, omit, and process information.

Video of the illusion (with instructions) here: https://www.youtube.com/watch?v=vJG698U2Mvo&amp;feature=youtu.be

NPR story discussing the experiment/illusion in simple terms: https://www.npr.org/templates/story/story.php?storyId=126977945