There are two parts to the process,

There are two parts to the process, first, the restriction of the
language used to a particular dialect and register; and secondly the selection from within
the register of the items that are to be taught according to criteria such as 'frequency of
occurrence', 'teachability' and classroom needs. The whole process must be applied at all
levels of language, so that unlike conventional vocabulary selection, which deals only
with items labeled 'words' but in fact having no clear linguistic status, the inventory of
teaching items is reached by considering phonology, grammar, lexis, context (semantics)
and extra linguistic situation at every point in the process.