Expansion is the concept of building additional language onto an utterance produced by the child. This is done by adding additional words to make a more grammatically correct phrase from the child’s production. Expanding on the child’s utterance provides the child with a more complex model to learn from. For example, if the child were to say “Baby.” while holding a bottle, the parent could expand their utterance by saying, “Baby is hungry” or “Baby wants bottle”. The child is provided with additional information surrounding their initial utterance while hearing a model that is slightly more complex than their own (Paul & Norbury, 2012).
A similar way to expand a child’s utterance is called “recasting”. When recasting an utterance, the parent again adds additional information to the child’s utterance. Rather than producing the phrase as the same type of grammatical form (i.e., if the child’s utterance is a statement, the parent’s utterance is also a statement), the parent phrases it as a different grammatical form, including as a question or as a negation (Paul & Norbury, 2012). The child may say “doll sleep”, and the parent could recast the utterance to say “The doll isn’t sleeping” or “Is the doll sleeping?”. This provides them with information supplemental to their initial utterance and also in a different form.
When a child hears an expansion or a recast of their own utterance, they are more likely to imitate a portion of the parent’s phrase without additional prompting as the phrase is directly related to something that holds their interest (Paul & Norbury, 2012). Expansions and recasts may be most effective if the phrase is crafted to fall within the child’s Zone of Proximal Development (ZPD).