Notes

11. I noticed that all the other possessive pronouns end in an 's', but in standard English, the possessive pronoun for "me" should be "mine". However, I think that "mines" is a perfectly logical comparison to "mine" because "mines" follows the pattern of ending in 's', whereas "mine" does not. It should make sense for possessive pronouns to follow a specific pattern, for logical and for simplicity sake. 

8. Somebody left their glasses on the streetcar.
Yes, it is grammatical. This sentence is generally accepted by the majority of English speakers
She don’t know about the race. 
Yes, it is grammatical. It may not be standard English, but that doesn't make it not grammatically correct
*He been lost in the woods for over a week. 
No, it is not grammatical.
*He been lost in the woods for over a week.
This sentence is not grammatical because it is not standard English nor is it non-standard. In other words, it is not generally accepted by English speaker since it's missing a word between "He" and "been": has or had. 
*There is twenty students that forgot to return library books. 
No, it is not grammatical.
*There is twenty students that forgot to return library books. 
This sentence is not grammatical because the conjugation of the verb "to be" is wrong. It should be "There are twenty students that forgot to return library books." instead of "There is twenty students that forgot to return library books."

6. Prescriptive - This statement is saying that starting a sentence with the word "because" is wrong and not "correct English". It claims that starting a sentence with a conjunction like because is not logical as it turns the sentence into a sentence fragment. However, starting a sentence with "because" is not inherently wrong as it does not take away from the meaning behind a sentence and can still be understood by others. 
Prescriptive - This statement appears to say that any educated person would not say "ain't" as it is "not proper". If this statement was descriptive, "ain't" would be a perfectly fine word to say since according to descriptive linguists, "Languages are continually changing in subtle ways without reducing their usefulness,  preciseness or aesthetic value." However, because this statement is saying the use of "ain't" is wrong, by process of elimination, this statement is prescriptive.