Telling that a grade is fixable and is not permanent.
Assuming that you're referring to the excerpt about slang in common english language according to Mario Pei : The tone is Neutral
you can feel that the author barely display any emotion in his explanation that written in the excerpt
hope this helps
The correct grammar would be “I got the teacher to explain the lesson”. I hope this helped
Personally, i think the topic should have several angles and for it to be specific