Published almost half a century ago the Segregation Model is the most commonly invoked example of how simple and abstract models can give you big and very real knowledge (and a Noble Prize).
The idea is so simple that it is sometimes used as beginners tutorial in NetLogo but recently it got a beautifully crafted new interactive visualisation by Vi Hart and Nicki Case, which you can find here.
Imagine a happy society of yellows and blues. The yellows quite like the blues and vice versa but they also like to live close to other yellows. Now the key element of the story is that even if that preference of living among members of your own group is very slight (we are taking 30%) it leads to a creation of segregated neighbourhoods. Yes, the actual segregated neighbourhoods where yellows live with yellows and blues live with other blues. One would struggle to call anyone racist because they wanted to live in an area where one third of their neighbours are of the same sort yet these harmless preference may create a harmful environment for everyone.
This is a very counterintuitive (and probably for that reason nobody figured it out earlier) but the Hart and Case implementation of the model allows everyone to test it for themselves. The playable guides you through the process and allows you to test different scenarios. They also include a nice extension – it turns out that even a slight preference for living in a diverse neighbourhood will revert the segregation pattern.
And on that cheerful note: happy winter break everyone!