Theme: Fundamental Forces of the Universe
Why this theme, well, the forces of the universe is responsible for everything that we observe, including that apple which fell on Newton's head. Each force has it's own unique characteristics and can represent each of the 4 words Chinese motto of the school

House Names: Gravity, Electromagnetism, Nuclear Strong and Nuclear Weak
Gravity - Where size matters, the more people you get, the greater your gravity is. So this represents unity
Electromagnetism - Lightning, electricity, magnets. This represents power
Strong - the force that holds protons together in a nucleus, it acts over small distances but it leaves an impression to us all. This represents impact
Weak - the name is weak but the force is not. This force is responsible for radioactive decay where changes take place. This represents change or creativity.

House Logo: Superstring theory - the idea that may unify all 4 fundamental forces, urmm houses, under one theory.
String theory logo (from wikipedia) sorry, no colour

Heh heh... Physics is Phun