Why do Dill and Jem want to give Boo Radley a note? How does Atticus react to their plan?

They wanted Boo Radley to come outside so they could look at him. They attach a note to the end of a fishing rod as to not get too close to his house. Atticus admonishes them. He says that if they want to see Boo Radley, they can knock on the door and treat him like a human being and not a circus side-show. He also adda that Boo is entitled to his privacy away from the gawking eyes of kids.

They are children. They are curious about all the rumors they've heard. Dill is especially curious because his own life is so dull. The boys also want to prove their bravery. Anyone who dares to do anything with Boo Radley is a brave man indeed.

They wanted to punish him

They wanted Boo Radley to come outside so they could look at him. They attach a note to the end of a fishing rod as to not get too close to his house. Atticus admonishes them. He says that if they want to see Boo Radley, they can knock on the door and treat him like a human being and not a circus side-show. He also adda that Boo is entitled to his privacy away from the gawking eyes of kids.

They are children. They are curious about all the rumors they've heard. Dill is especially curious because his own life is so dull. The boys also want to prove their bravery. Anyone who dares to do anything with Boo Radley is a brave man indeed.

They wanted boo to come out side.

Yes, Tiffany, the children wanted to see if Boo would come out.