Need
discussion: you and your shadow
light can be transmitted through, reflected by, or absorbed by objects. white light contains all the wavelengths of visible light—all the colors of the rainbow. your eyes are able to determine colors of objects due to the absorption of certain wavelengths of light by those objects.
how is your shadow proof that light travels in a straight line?
how does use of a prism work and how does it prove that white light combines all the wavelengths (and colors) of visible light?