This tutorial is also still under construction.
Please do use the resources that ARE here though.
Clipbank video learning resources.
Extracted from educational programmes for secondary schools aired on Channel 4.
Bill uses a bucket of propylene glycol to show how a fiber optic cable works and how engineers send signal across oceans.
This is A LOT more info than you need - it's fascinating, but at this point you only need the first 2 minutes about an optical fibre using total internal reflection to transmit an EM signal.