I'm going to talk to a couple of 8th grade science classes today, and like any self-respecting visual neuroscientist, I'm loading up on some visual illusions.
Last night, while being bored with my presentation, +Judy Cam made an excellent point. If you think that all you have to do is "trust your gut" when it comes to understanding science then you've got an uphill battle. Visual illusions are a prime example of this. We often see things that do not exist. Yet, if we trusted our gut, relied purely on our senses, then we would argue that those spirals below are totally spinning.
It's through the careful application of the scientific method that we can parse out the false movement in the picture below, or false correlations in vaccines and autism, or validating correlations between human behavior and climate change.
Edit: This illusion can be found in many places, but I got it from +Kristina Visscher. Thanks, Kristina!