This is based on very clear and focused use of correction techniques and could be a short teaching phase in a lesson about something else, or a whole lesson or part of a lesson. It is about taking things learners say and helping them to achieve greater accuracy. It works well as a whole lesson when you only have a few learners and are chatting with them.
The core technique is as follows:
A learner makes a useful error in saying something he or she wants and needs to say: eg Why you late? when another learner arrives late.
Repeat what the learner says using questioning intonation and invite the learner who make the utterance then other learners to try to correct it. (if it’s a longer, more complex sentence you might need to write it on the board). If learners can’t correct it, use your fingers to indicate missing words or word order problems.
Ask learners why the sentence was wrong – they need to understand eg that the sentence needs a verb, that a question needs inverted word order. If necessary write the sentence on the board and highlight these things. Give learners time to absorb and understand.
Rub it off the board and drill the class chorally and individually, making sure you get the original student to repeat the utterance.
Get them saying it to each other, if possible in parallel situations: Why were late yesterday? Why are you always late? etc.