In young children's language development, which construction typically emerges last?

The statement "He's playing" involves the use of the present progressive verb tense, which indicates an ongoing action. In young children's language development, mastering different verb tenses is a gradual process. Typically, constructing sentences that appropriately use the present progressive can be one of the more challenging aspects for young children because it involves not only understanding the concept of ongoing actions but also the necessary verb forms and auxiliary verbs ("is + present participle").

In contrast, the other sentence constructions provided—such as "He's being silly," "He runs fast," and "She has a toy"—typically emerge earlier in children's language development. These sentences involve either basic present tense or simple descriptive verbs, which are generally easier for young children to formulate. Therefore, "He's playing" is often one of the last constructions to appear as children's language skills develop, reflecting their growing understanding of complex sentence structures and verb forms.