What more does the reader learn about Tom Robinson’s arrest? Of what has he been accused? Who has accused him?

These questions have been answered in earlier chapters. Tom Robinson has been charged for the rape of a white girl named Mayella Ewell. Bob Ewell, her drunken father, falsely accused Tom of rape. In chapter 12, Scout asks Reverend Sykes why Helen needs the collection money when she can still go to work and take her children with her. Reverend Sykes explains that she may have trouble getting any work in the fields now. Scout asks Calpurnia about this, and Calpurnia explains that it's because Tom has been accused of raping Bob Ewell's daughter. Mr. Ewell had Tom arrested and put in jail. Scout remembers that the Ewells are the ones who only come to school once a year, and are what Atticus calls "absolute trash." Calpurnia won't tell her what rape is.