To Kill a Mockingbird Ch,7,8,9

In chapter 7, the whole "hole in the tree-trunk" mystery wasn't exactly too much of a mystery to me. I'm quite certain that Arthur Radley had been putting those there as a means to try to get some outside contact, since he's stuck inside all day. However, there's a possibility that Nathan Radley put concrete inside the tree hole just to stop Scout and Jem from entering his lawn. As for chapter 8, it showed the truth about Arthur Radley, put more obviously this time, rather than unreliable stories or having to infer from the text. This chapter was very clean-cut, and not many things were exactly implied, however, I don't know why Jem just broke down and admitted everything to Atticus, who thankfully wasn't listening. Chapter 9 felt like it was meant to teach the reader about the themes of the book more than anything. Since there were mainly adults talking, it was a lot easier to understand. In this chapter, Scout feels a lot more bearable to listen to, since she's learning more about the world.