A child who says "that dog" is in which of Brown's stages of Syntactic and Morphological development?

The child saying "that dog" indicates the use of a noun phrase consisting of a determiner ("that") and a noun ("dog"). According to Brown's stages of syntactic and morphological development, this demonstrates the use of basic sentence constructions, typical of Stage I. At this early stage, children begin to combine words and show an understanding of simple grammatical functions.

In Stage I, which typically occurs between 12 to 24 months of age, children produce one- or two-word utterances that reveal an emerging structure to their speech. The utterance "that dog" follows this pattern, showcasing the child’s ability to refer to a specific object and combine a determiner with a noun.

Later stages of development involve more complex grammatical structures, including the use of verb phrases, plurals, and the correct application of verb tenses, which are not reflected in the phrase "that dog." Thus, identifying this utterance as occurring at Stage I accurately describes the child's developmental capabilities at that point in their language acquisition.