When do children first use some rules of grammar?

It's a complex question! Children don't suddenly "use" grammar at a specific age like flipping a switch. Instead, they gradually develop their understanding and use of grammatical rules over several years. Here's a breakdown:

Early Stages (1-2 years):

* Single words: "Milk," "Ball," "Up!"

* Two-word phrases: "Want juice," "Mommy gone."

* Basic sentence structure: "Daddy sleep," "Doggy bark."

Preschool Years (3-5 years):

* Longer sentences: "I want to go outside and play."

* Basic verb tenses: "I played with the blocks," "I will eat dinner."

* Plurals: "Two cats," "Many toys."

* Possessives: "My toy," "Daddy's car."

* Simple questions: "Where's the ball?" "What are you doing?"

Elementary School Years (6-12 years):

* More complex sentence structures: "The dog chased the ball down the street."

* Understanding different parts of speech: nouns, verbs, adjectives.

* Grasping more advanced grammatical rules: subject-verb agreement, past participles, conjunctions.

* Mastering written grammar.

Important Points:

* Individual Variation: Every child develops at their own pace. Some might pick up grammatical rules faster than others.

* "Telegraphic Speech": This early speech omits function words like articles ("a," "the") and prepositions ("on," "in") but still conveys meaning.

* Overgeneralization: Children sometimes apply rules incorrectly, like saying "goed" instead of "went," showing their understanding of grammatical patterns even if not entirely accurate.

So, there isn't one specific age when children "use" grammar. It's a continuous process of learning and refinement throughout early childhood and beyond!