Forget what your professor told you.

Linguistics is essentially a study of the way we use words to communicate with one another.  Because language is dynamic, that is, it is always changing to meet our communication needs; there is not really any right or wrong way to use language in communication.   Linguistics represents an effort to slow down and pay attention to patterns in language use.  These patterns repeat themselves throughout the English-speaking world regardless of the ways many English speakers change that language for their own needs.   As each generation changes English words and phrases for their own reasons, they are still caught in the conformity of the language.

Consider the phrase: "fo' shizzle my nizzle".  (Urban Dictionary) An English speaker, without understanding the meaning of the phrase can recognize the grouping of words as something that could be said in English.  "Nizzle" has the sound of a noun, and is preceded by the possessive "my".   "fo'" may be picked out as short for "for", as linguistically the sounds are patterned the same phonetically, especially in some American dialects.

The bottom line is that all variations of English follow structural rules that native English speakers learn through patterning and repetition.  We do not, therefore, learn grammar and linguistics to improve our language skills; we learn grammar and linguistics to grasp a deeper understanding of the language skills we already possess.

Conversely, this is also part of what makes Grammar and Linguistics so difficult for English speakers.  The task should be one of critical thinking and self-awareness, yet in the world of academia, of correct and incorrect and of building tasks to demonstrate knowledge, this reality is lost. 

Linguistics is more philosophy than science.  Learn to enjoy that self-awareness and the subject will open up for you. Next Section next.

 
         Urban Dictionary: fo’ shizzle my nizzle, Urban Dictionary, 10 November, 2002, 
March 23, 2008 http://www.urbandictionary.com/define.php?term=fo'%20shizzle%20my%20nizzle