This article describes a two-day optics laboratory activity that investigates the scientific phenomenon of reflection, which students are generally familiar with but usually have not studied in depth. This investigation can be used on its own or as part of a larger unit on optics. This lesson encourages students to think critically and…

With an aquarium and a few tools, a simple apparatus to quantitatively illustrate absorption rates of light passing through fresh, salt, and other waters (such as distilled water) can be constructed. Students learn that extinction rates are different and that the intensity/depth relationship is exponential. (DH)

Describes an apparatus (called the "Rainbow Cup") used for demonstrating the colored rings produced by constructive interference in soap films. Discusses construction of the Rainbow Cup and gives hints for its use in the classroom, especially in relation to classroom humidity. (JM)