Alex, Amy's older brother, appears more teenage despite both being fifth graders. His scientific and inquisitive nature drives him to approach situations with logical reasoning. As a member of the group including Tom, Amy, Mark, Bob, and Laura, he leads their summer adventure planning to investigate strange sounds from nearby Mount Pinto, stressing strict schedule adherence. Upon discovering a pit filled with a sparkling soap bubble-like substance, Alex insists on collecting a sample for study while the others impulsively play. He navigates methodically, marking their mountain path with a rope. This careful system falters when a bug chews through the rope, contributing to the group becoming lost. Throughout, Alex consistently exhibits analytical thinking and a preference for structured exploration.