The average student, especially the average non-middle-class-or-higher student, believes he or she talks wrong. To liberate students from this misconception should be a prime goal of English teachers.
I asked a college basic prep class (that is, students needing a semester's extra prep before undertaking regular first-semester writing classes): "What is the difference between standard English and nonstandard English?"
One student responded, "Standard is right. Nonstandard is wrong."
Thus the student handed me the key to unlocking the prison door--a student always gives me some kind of key when I ask that question. It takes seconds to explain that no form of a language is right or wrong. "if I talk so the important people in my life understand me," I tell them, "then I am talking right." To point out that every student has mastered numerous forms of English already (the forms appropriate for interacting with friends, with sports teammates, with parents, with elders, with teachers, with work supervisors--forms that include specific vocabulary sets) takes another minute.
By now every student's eyes are fixed upon me. Gone is the mud that had until then besmirched their linguistic self-concept. Open are their ears. Now I can explain that standard English is not the right form versus the wrong form, but a tool to master for their own purposes. Standard English enables them to express vital ideas to a wide audience because it is internationally used and can be made precise.
"If there are words in textbooks that you don't know, it is not because you talk wrong, but because you have not needed those particular words before," I add. "You have dictionaries available to you through your smart phones. Use them to help you acquire this tool--standard English."
Students enjoy informally racing each other to see whose smart phone can find a definition the fastest. They become alert to how grammar works rather than viewing grammar as a trap in which they will inevitably get snared. Their resistance to learning standard English is gone because I have spoken what they knew deep in their hearts: to say that standard English is right and their forms of English are wrong is unjust.
As Charles Dickens articulates in Great Expectations, children are keenly affected by injustice. Too many students come to a basic prep class with silent anger that has been with them all their lives. When I demolish the Prison of I Am Wrong Because I Talk Wrong, my students are freed to engineer their own progress as writers at the college level.