…rging ideas first by exploring the extreme ends of the landscape you defined in the previous stage: go as far into one extreme possible solution as you can, then jump to the other end of the spectrum and do the opposite. Repeat until you begin to formulate a more realistic vision of a possible solution.
Write everything asked and answered down. Draw if you have to. Half the time you spend on the challenge should be asking questions, writing down assumptions, and aligning on definitions/goals with the other person in the room.