TEACH IT CLEARLY.
Learn something hard, then teach it without notes.
You only understand an idea when you can explain it out loud with nothing to read from. Example, limitation, common mistake: all three.

THE CHALLENGE
Learn a difficult idea, then explain it out loud without notes. Include an example, a limitation and a common misunderstanding.
WHY IT'S HARD
Understanding is demonstrated through explanation and examples.
DO IT RIGHT
Any accessible format counts: text, audio, assistive tools. Care and emergencies always come first.
HOW IT WORKS ON HARD.
Everyone gets the same challenge on the same day. Say I'M IN, take as long as it takes, then say I DID IT on your word. Your friends see you show up.
ON THE RECORD
IT COMES BACK. NOBODY KNOWS WHEN.