As she is facing the problem in understanding of the chapter from the text book, I will explains the points that are mentioned in the class from my notes.
I will ask exactly which point she is unable to understand and which points she is able to understand. Then I will see if she understands, the points told by the teacher. More than that, it is difficult to explain. I will explain her by doing one exercise at the end of the chapter and explain the worked out example.
More than that, I can advise her to see some other resources. She may contact the teacher the next day, and seek a proper advice.