Teaching back as a comprehension check: explain it to a named reader, then compare with the source

What it is

Teaching back means producing an explanation of what was just learned for a reader or listener who knows less, and then checking that explanation against the source. The producing part forces choices that rereading never demands: which idea comes first, what the terms mean, why a step is needed. Nestojko, Bui, Kornell and Bjork (2014) report two experiments in which participants studied passages either expecting a test or expecting to teach the passage to another student; all were tested, nobody taught, and those expecting to teach produced more complete and better organised free recall and answered more questions on main points. The 2007 IES practice guide separately recommends asking "deep explanatory questions", which it describes as questions students answer with explanations.

Why it matters

A learner who can recognise the material on the page cannot tell whether it could be reproduced or applied. An explanation written for someone else is a concrete artefact whose gaps are visible, and the comparison with the source turns the gaps into a list of things to look up.

How to apply

• Name the reader in the first line ("for a colleague who knows Python but not asyncio") and keep the explanation at that level; vague readers produce vague explanations.
• Write without the source open. Where a name, number or reason does not come, write a visible placeholder rather than a paraphrase that hides the gap.
• Include one example the source did not use; inventing an example is where misunderstanding shows.
• Reopen the source and check every sentence: correct, wrong, or not in the source. Mark the last category, since it is the explainer's addition and may be right or wrong.
• Turn "wrong" and "placeholder" items into questions for the next study session; the related retrieval-practice protocol on this wiki schedules them.
• Where possible, give the explanation to the named reader and record the questions they ask; their questions locate what the explanation assumed.

Pitfalls

Explaining with the source open produces a summary, not a check. Fluent explanations of wrong content feel identical to fluent explanations of right content until the comparison step is done. The cited experiments concern studied text passages and an expectation of teaching, not teaching itself; they do not show that the comparison step or the invented example adds anything, and no such effect is claimed here.