How does Atticus respond when he suspects what Scout, Jem, and Dill are doing?

Jem comes up with the idea to play a game about Boo Radley and his family.  The game is based on a basic script with roles.  Scout plays Mrs. Radley, Dill plays Old Mr. Radley, and Jem plays Boo.  The key scene in their game is when Boo stabs his father in the leg with a pair of scissors.  When Calpurnia is not looking, they take a pair of sewing scissors from the drawer where the sewing supplies are kept.  Jem pretends to stab Dill in the leg with the sewing scissors.

One day, they are playing their game outside the house and they do not notice "Atticus standing on the sidewalk looking at [them], slapping a rolled magazine against his knee" (To Kill a Mockingbird, Chapter 4).  He sees them playing their game with Jem holding the scissors.  Atticus asks the children what they are doing, but Jem evades his father's question.  Atticus asks about the scissors, but Jem continues to evade the question.  Atticus is suspicious:

"Give me those scissors," Atticus said.  "They're no things to play with.  Does this by any chance have anything to do with the Radleys?"

"No sir," said Jem, reddening.

"I hope it doesn't," he said shortly, and went inside the house.

Atticus suspects that the game is about the Radleys, but he does not know for sure.  He chooses not to accuse the children, though he expresses his disapproval of a game about the Radley family.