In a standard language focus lesson following a PPP (present, practise, produce) or similar format, the target language (structure or vocabulary) is normally presented in context, then isolated and analysed.
Analysis of the language consists of two sub-stages, often known as highlighting and concept checking.
Highlighting is taking the model sentence and showing, telling or eliciting what the problems are in terms of form, function, and phonology.
Concept checking is checking the understanding of difficult aspects of the target structure in terms of function and meaning. Concept checking is vital, since learners must fully understand the structure before any intensive practice of form and phonology is carried out.