When you shout the word “go,” the runner runs to the message, reading and remembering what they can. This can be as much as a few sentences or as little as one word. The aim is to be able to relay it accurately to the writer.
The runner goes back to the writer to relay the part of the message that they memorized. The writer (you guessed it!) writes it down.
Repeat until the message is complete. Teams score points for speed but more importantly for accuracy of spelling and punctuation.