Chaos Theory. The science of organisation within a complex, dynamic system. The idea that apparently pure randomised systems still operate within rigid laws.
I once tried applying the principles of chaos theory to my lessons - stopped assuming I could outlaw poor behaviour, recalcitrance and moments of fury - simply decided perhaps these outbursts were inevitable, and planned my response.
It was the best lesson I'd taught in three years, and it taught me that while working in an inner city school, certain things within the rigid system can be permanently relied upon: namely, the presence of a deterministic, controlled rebellion, that is actually quite the opposite of 'chaos'.