Plain English Meaning
A short moment when something has just happened that makes the student really want to learn a particular point — and an alert instructor uses that moment to teach it, because it will stick far better than if taught at a planned time later.
Full Definition
A brief window during instruction when a learner is unusually ready and receptive to absorb a specific lesson, typically created by an event, question, mistake, or experience that has captured the student's attention and made the relevance of the lesson immediately obvious.
Context Anchor
Seen in aviation instructor training when discussing learner readiness and how an instructor chooses when to explain, correct, or reinforce a point.
Derivation
From 'teachable' (able to be taught) and 'moment' (a brief point in time). The phrase highlights that is time-sensitive — the opening can close quickly if not used.