> Spoken languages are like that too. A 3 year old doesn't know what verbs are. They just speak. Not sure how you meant this to be understood, but a 3 year old

> Spoken languages are like that too. A 3 year old doesn't know what verbs are. They just speak. Not sure how you meant this to be understood, but a 3 year old definitely knows that there are different word classes that behave differently. They don't know that they're called verbs, nouns, adjectives, etc. but they do correctly (to a large enough extent) use grammar applying specifically to the different word classes.