Plan and carry out an investigation to determine the effect of materials in the path of a beam of light. Emphasize that light can travel through some materials, can be reflected off some materials, and some materials block light causing shadows.
In the last unit, students explore how objects can be seen when they are illuminated by a source of light and how light passes through opaque, transparent, and translucent materials differently. In this unit, students apply what they have learned about light and sound to design a solution that can be used to communicate over a distance.
