One switch that turns every radio off at once. Flicking it on and straight off again is the quickest way to make a stuck phone find the network afresh.
The drawing that proves the sentence above. It is the same card that is in the book.
Think of it as
a single switch that closes all the windows.
For example
Your phone says it has signal but nothing loads. You switch airplane mode on, wait a moment, switch it off — and it works.
This is one card out of 275.
The hundred words you meet most are free — the whole set, animated, in one file that works with no internet.
Volume 1 has all 275 in fifteen chapters, with Staying Safe the largest chapter on purpose.