Why does Jonas take the apple home?

Jonas takes the apple home in The Giver because he sees it mysteriously change while he and Asher are tossing it back and forth, and he wants to study what happened.

At that point, Jonas does not understand that he has briefly seen the color red. He only knows that something impossible seems to have occurred: “The apple had changed. Just for an instant. It had changed in mid-air.” Asher does not notice anything, which makes the moment even stranger for Jonas. Since their community discourages calling attention to differences, Jonas keeps the experience to himself rather than asking others about it openly.

Taking the apple is still against the rules. The Speaker later makes an announcement aimed at Jonas without naming him directly, saying, “snacks are to be eaten, not hoarded.” Jonas apologizes for taking it, which shows that he still believes in the community’s rules and feels guilty about breaking them. His curiosity, however, shows that he is already different from the people around him.

Jonas seeing the apple's red color is an early sign of his "Capacity to See Beyond," the rare ability that later helps make him the next Receiver of Memory. A small rule-breaking act begins with confusion and curiosity, then becomes part of the larger pattern of Jonas discovering the knowledge that his community has tried to erase.