I think Boo was laughing. Boo was isolated and didn't really have a childhood so his laughter wasn't really in the interest of the children, but shared in their enthusiasm and ineptness...
Scout heard someone laughing inside the Radley house when she rolled into their yard, which made her feel scared and uneasy. This laughter added to the mysterious aura surrounding the Radley family and their reclusive lifestyle.
Scout heard laughter and someone inside the Radley house saying, "Do our neighbors bore you, Dill?" This made her concerned and curious about the mysterious Radley family and their behavior.
yes she thought she heard Boo laughing whilst on the patio when she and the boys were playing at rolling in the tyre.
Boo was laughing because he found the children's' game funny. He was an innocent character and wanted to join in with them but he didn't know how, so he just laughed with them from inside his house.
Scout heard someone laughing inside the Radley house, but she never told anyone about it. This mysterious laughter added to the rumors and stories surrounding the reclusive Radley family.
She heard laughter from the Radley house.
Atticus returned home to Maycomb to defend Tom Robinson, a black man wrongly accused of raping a white woman.
Scout wanted to quit the game because she realized that Boo Radley had been watching them all along, and felt guilty for making fun of him. Rolling the tire towards the Radley house made her see things from Boo's perspective and understand that their games were not harmless but could actually be hurtful.
someone inside the house was laughing (pg.54)
someone laughing!
Scout overhears her brother, Jem, telling Dill about a series of small gifts they found in the knothole of a tree on the Radley property, speculating that Boo Radley must have placed them there, suggesting that Boo is alive and potentially watching over them.
the laughing she heard from inside the house and atticus found out"Atticus's arrival was the second reason I wanted to quit the game. The first reason happened the day I rolled into the Radley front yard. Through all the head-shaking, quelling (trying to stop) of nausea and Jim yelling, I had heard another sound, so low I could not have heard it from the sidewalk. Someone inside the house was laughing."Scout is scared of the laughing she heard from the Radley house when she rolled in the tire, and Atticus was already suspicious that the children were acting out Boo's legend, or the "Boo Radley game."