year-old girls built the beeping walking stick for a class project at their UN-funded girls' school. The cane uses two infrared sensors, one front-facing and one in the tip of the cane, to detect obstacles and drop-offs. The students produced two prototypes after making multiple trips to Ramallah and past two Israeli checkpoints, to scour electronics stores for proper circuits and sensors. The girls' design resolves a fundamental flaw in previous models by detecting holes in the ground. The cane beeps when it passes over a hole or steps going downward. __