In my copy of To Kill a Mockingbird, Scout refers to the prejudiced comments made by Miss Gates on page 247. Of course, this may not be exactly the same page number as your copy, but you should be able to find it if you look within one or two pages (at most) before the beginning of Chapter 27.
At this point in the novel, Scout is trying to make sense of Miss Gates' hypocrisy. Scout has believed Miss Gates to be a decent person and knows that the teacher hates Hitler because of his cruelty toward the Jews and other minorities. However, Scout overhears Miss Gates make a cruel racist remark while leaving the courthouse after Tom Robinson's trial and cannot seem to understand how one person can claim to feel so strongly about persecution by one person while practicing it herself.
"Well, coming out of the courthouse that night Miss Gates was--she was goin' down the steps in front of us, you musta not see her--she was talking with Miss Stephanie Crawford. I heard her say it's time somebody taught 'em a lesson, they were gettin' way above themselves, an' the next thing they think they can do is marry us. Jem, how can you hate Hitler so bad an' then turn around and be ugly about folks right at home--"