Science and its fields.. What's the best way to break it all into categories?

[Bio-Hazard]

What's the best way to break all the science subjects into a tree like structure? I have a bunch of forums I go, and I'm trying to make a type of tree system, but yet I don't know what the best way to do this type of system would be.

Science
- Physics
-- Mechanics
--- Security Engineering

Would that be proper?

Does anyone know of a huge tree structure I can look at? Has one ever been built like the 5 animal kingdoms?

[Tormod]

Good question. We've discussed it a couple of itmes but never really came up with anything.

I suggest looking for how for example DMOZ organizes their science categories. Or ask at a library...