1) Most studies suggest that elaborative feedback (an explanation) tends to be no more useful than telling a student the correct answer. But most studies only ask retention questions.

2) In this experiment, students read texts, answered questions, then received either the correct answer or an explanation. Two days later, they were asked either retention questions (definitions) or ‘inference questions’ (harder!).

3) Students who'd received explanatory feedback did no better than those who'd received correct answer feedback for definition questions (you probably retain the right answer anyway). But explanatory feedback led to better results on inference questions.

4) Implication: explanatory feedback makes a difference, but only on things students need to think hard about - not for simpler questions. https://www.ezyeducation.co.uk/images/EzyEducation/ButlerGodboleMarsh.pdf

PS: Distinction between correct answer and explanation feedback as used in the paper.