What evidence in To Kill a Mockingbird shows that Jem is beginning to understand more than Scout about Boo Radley?Starting in chapter 7.
My favorite piece of evidence in regards to Jem's epiphany comes in Chapter 7. Jem begins to realize that it is truly Arthur Radley who is putting the special treasures in the tree; however, Scout doesn't begin to realize this until sometime later. For example, after finding so many little trinkets and goodies, Jem decides they should write a letter thanking the person who is befriending them. At this point, Jem suspects. This is revealed right in the middle of Chapter 7:
[Jem] had been on the verge of telling me something all evening; his face would brighten and he would lean toward me, then he would change his mind. . . . "Okay. Dear Mister . . ."
"How do you know it's a man? I bet it's Miss Maudie--been bettin' that for a long time."
"Arr, Miss Maudie can't chew gum--" Jem broke into a grin. (Lee 61)
The "something" that Jem is considering telling Scout is simply the revelation that it is Boo Radley who has given them such glorious things in such an unusual way. Jem, of course, is older than little Scout. Scout is even shocked (and a bit upset) in Chapter 8 when Arthur Radley comes up behind her to place a blanket over her shoulders. This is just another example of how Jem comes of age through To Kill a Mockingbird and how Scout always manages to be behind the curve.