How did Nick and Marta gain entry into Mrs. Starch's house?

Nick and Marta gained entry into Mrs. Starch's house by finding a key on the porch. This method of entry suggests that they were resourceful and might have known where to look for a spare key. It's common for homeowners to hide spare keys for convenience, and discovering such a key would allow them to enter without drawing attention through more conspicuous actions like knocking or asking someone else for entry. This detail highlights their cleverness and aligns with typical scenarios in stories where characters seek convenient solutions to obstacles they encounter.