Writing instructions for someone who is frightened
We tested the evacuation page with people holding a phone at arm's length in a dark stairwell. Every sentence that needed a second read got cut.
Plans are usually written by calm people for calm people. The failure mode shows up the moment someone is tired, cold, or carrying a child: they skim, they misread order, they stop.
So we set a rule. Each step is one action with one object, in the order you can physically perform it. No step refers to another step. Nothing depends on remembering what you read thirty seconds ago.
The second rule is about type. Minimum 17px on screen, and the printed sheet is set at 12pt with generous leading, because the printed copy is the one that gets used when the phone is dead.
We also removed every instance of the word 'ensure'. It tests badly. People do not ensure things at two in the morning; they close a valve, or they carry a bag.