"You’re sitting in a room. There is a door into the room with a
letterbox. Every now and then a piece of card with a squiggle
shape drawn on it comes through the door and drops on your
doormat. Your task is to look up the squiggle in a book that
is on the table in the room. Each squiggle is paired with
another symbol in the book. You have to find your squiggle in
the book, look at the symbol it is paired with, and then find
a bit of card with a symbol that matches it from a pack in the
room. You then carefully push that bit of card out through your
letterbox. That’s it. You do this for a while and wonder what’s
going on."