What is a "judgment of learning" (JOL), and what does "calibration" mean?

A judgment of learning (JOL) is your prediction that you'll be able to recall something later; calibration is how well those predictions match your actual performance.

A well-calibrated learner's confidence tracks reality: high confidence on things they truly know, low confidence on things they don't. A poorly calibrated learner is confidently wrong — sure they'll recall material they'll actually blank on.

Calibration is the practical payoff of metacognition. Poor calibration causes bad study decisions: you stop studying things that feel known but aren't, and you'll only discover the gap at test time, when it's too late to fix.