Why does a spoon look bent in water?

This phenomenon is due to the refraction of light. When light travels from one medium to another, like from water to air, it changes its speed and consequently its direction. The light rays coming from the part of the spoon submerged in water bend away from the normal as they exit the water and enter your eyes. Our brain, however, assumes that light travels in straight lines. Therefore, it traces these bent rays back in a straight line, making the submerged part of the spoon appear to be at a shallower depth and slightly displaced from its actual position. This apparent shift in position makes the spoon look bent or broken at the water's surface.