Speedrunning as an Emergent Property
One of my favorite concepts to teach is emergent properties. These are phenomena like friction or surface tension that exist because of the scaling up of the behavior of individual molecules. Something where the whole gets new properties because of the sum of its parts. Take the states of matter - a single water molecule isn't a solid, liquid, or gas, it takes a collective interaction of the molecules to get properties like that! You could argue that Science is just the collective layers of abstraction of these properties, from studying single particles in Physics to molecules in Chemistry up to complex cells in Biology.
This can be a difficult topic to internalize, especially when so much of early education focuses on strict categorization or facts. So the more engaging examples and analogues I can find, the better! One of my favorite analogies is video game speedrunning. It's not a great example since most folks aren't even aware of it, but it paints such a great picture of how individual pieces of code can lead to unexpected results when scaled up.
Speedrunners will rely on quirks like two unrelated objects in a game relying on shared memory for efficiency to zoom through a game. The programmers never intended something like a victory pose moving a character 1 pixel backwards leading to a way to slide through boundaries into other levels. Even if they scoured their functions for potential bugs, things like that wouldn't stand out in any meaningful way. It is only when the engine is running in its full complexity that these phenomena emerge.