Honestly chapters 7-12 are one of the more doable chunks of that book, so try not to panic. A few of those chapters are super short — 7, 9 and 11 are the little vignette chapters that are only a few pages each (the car salesman, the family selling their stuff, the empty farm). You can knock those out really fast.
What helped me with this book was reading the short chapters quickly and saving my energy for the Joad chapters (8, 10 and 12), because those are the ones your teacher will actually ask about — that’s where Tom reunites with the family and they start heading west.
Also, jot down one line per chapter as you go, like “ch 7: used car salesman rips people off”. It makes it way easier to remember everything the next day than trying to hold it all in your head. And try 25 minutes reading, 5 minutes break — five chapters is very doable in a couple of hours that way.
You’ve got this. And seriously, get some sleep after — being exhausted makes the reading twice as hard.
