An ELT Glossary : Reformulation

Definition : A technique used in giving feedback on erroneous/inappropriate/unnatural etc language, involving the teacher repeating the learner's utterance in the way that it might actually be said by a native speaker.

L : And we goed in London.
T : You went to London? When?

Useful because :
a) It allows the T. to "correct" the mistake in full class work without an explicit focus on it and without interrupting the flow of the discourse, either of which might unsettle the learner, while at the same time providing confirmation of the correct form for other learners who, if there was no correction, might become confused as to what the correct form actually was.

b) If the learners are aware that the T will be using the technique, it can encourage "noticing" which will also be useful for them when they are exposed to language outside the classroom.

Related Reading
Bartram, M. and Walton, R. Correction: A Positive Approach to Language Mistakes, Heinle ELT