Well, not to belabor the point, but “. .our grand kids don’t speak good Chinese” is then not grammatically correct, just as ‘don’t speak good English’, or ‘don’t play good baseball’ are. Which I found ironic considering the topic.
Here’s a simple example of the difference:
“My name is VanShuyten. I am from Lower Slobbovia.”
Those two sentences are good English.
If that is all I can say, I don’t speak English well.
Rachel Jeantel has several things going on. She probably speaks Ebonics, which is a dialect of English which relies on simplification of verb tenses, vocabulary, pronunciation, and sentence structures. ( Standard English also did that by dropping the Old English verb forms and conjugations for most verbs - eat, ate, eaten vs stop, stopped, stopped - and reducing the number and combinations of letters and pronunciations. The modern pronunciation of “knight” is much easier to us than the original, which was said much like it is spelled. Ebonics probably started with slaves from different African language groups using a simplified English to speak with each other.) She also probably never mastered Standard English, and it’s pronunciation and large vocabulary. Because of that, she was unable to completely “code shift” from Ebonics to Standard English and mixed the two. I think she also has trouble going from general, vague thoughts to precise speech, but there could be many reasons for that, not all having to do with her language ability.
There is another assumption by the author that because Ebonics is spoken, it deserves equality with Standard English. Thas retarted. The whole point of having a standard form is so that people with different dialects can understand each other. A person speaking Standard English can go to any place where English is spoken and be understood. That is why it is so important that all students master Standard English, and the failure to do that is just one example of how poorly our schools are doing.