In chapter 10 of "To Kill A Mockingbird," Calpurnia becomes aware of the sick dog walking up the street. The first thing she does is get the children, Scout and Jem, on the porch out of harm's way. The next thing she does is call Sheriff Heck Tate and Atticus to tell them of the rabid dog, Tim Johnson. They both arrive and Heck wants Attius to shoot the dog, but Atticus says he doesn't want to. He relents because Heck says if he misses the bullet will go right into the house behind the dog. Atticus hits the dog with the first shot and kills it. This is important because the children were feeling that their dad was old and not like the "other dads" in Macomb. This gives them a sense of newly discovered pride in their father. Calpurina's first responsibility was to make sure the children were safe.
Calpurnia handles the situation with the dog quite efficiently in Chapter 10 of To Kill a Mockingbird.
When she catches sight of Tim Johnson, Calpurnia clutches the children by the shoulders and hurries them home. Once there she shuts the wooden door inside the screened door; she then hurries to the telephone and shouts to the operator, "Gimmie Mr. Finch's office!" Then, Calpurnia informs him of a rabid dog in the neighborhood, urging him to attend to it.
After having contacted Mr. Finch at his office, Calpurnia asks the operator of the switchboard to inform the other people in the neighborhood of the circumstances. Because the Radleys have no phone, Calpurnia hurries down the block toward their house in order to inform them of the danger. When she reaches the Radleys' house, Calpurnia knocks on the door. Since no one answers, she shouts for them to stay in their home, and she states why. Soon, Calpurnia returns, and Heck Tate and Atticus pull into the driveway.
It is at this point that the chidren learn of their father's skill as a rifleman. Heck Tate insists that because of the direction the animal is going, there is only one chance to shoot the dog without hitting the Radley house; therefore, Atticus must use the rifle as he is more accurate. So, Atticus aims at Tim Johnson, who is coming down the street, and he quickly fires. The dog crumples, not knowing what hit him.
After seeing this, Jem is proud of Atticus because he realizes that all this time Atticus has been too much of a gentleman to boast of his skills. This is why Jem gleefully calls out, "Atticus is a gentleman, just like me!"