A shadow forms when an opaque object blocks light from reaching a surface. Its size and direction depend on the positions of the light source, object, and receiving surface. Shadows can reveal geometry without any special equipment. As Earth rotates, the Sun’s apparent position changes across the sky. A fixed object’s shadow therefore changes direction and length during the day. The exact pattern depends on location, season, and the object’s orientation. A low Sun commonly produces a longer shadow on level ground. Do not assume the shortest shadow always occurs at noon on a clock. Clock time and local solar time need not match. Use the same object and surface for a comparison and mark observations with their actual times. Never stare at the Sun to estimate its position. Practice: Trace a stationary object’s shadow at three times on a safe outdoor surface. Compare length and direction, then sketch the light path that explains the change.