Help!! 4th Grade Light Unit

I teach in a science discovery center. One of the units I teach is the 4th grade light unit. We do great activities with the light box and lenses to demonstrate the visual light spectrum and refraction. We've done an activity with the PASCO light sensors to help the students learn reflection and absorption, however, I don't feel my students are getting the main point that light colors reflect and dark colors absorb. Does anyone have a great activity. Ideally that uses technology?