Daisy May Johnson’s middle-grade novel “How to Be Brave” is a delightfully funny yet endearing story about a young girl named Calla North. To locate her mother Elizabeth, who has vanished, she teams up with her buddies from boarding school. Together, Calla and Elizabeth have a calm yet contented life. Elizabeth just so happens to be the foremost authority on this. The book celebrates friendship, bravery, and the wonder of having faith in the impossibility of things.