Make a pinhole camera, as illustrated below. Cut out one end of a small cardboard box, and cover the end with tissue or wax paper. Make a clean-cut pinhole at the other end. (If the cardboard is thick, make your pinhole through a piece of aluminum foil placed over an opening in the cardboard.) Aim the camera at a bright object in a darkened room, and you see an upside-down image on the tissue paper. When photographic film was in vogue, students replaced the tissue paper with unexposed photographic film, covering the back so that it was light-tight, and covering the pinhole with a removable flap, all ready to take a picture. Exposure times differed, depending principally on the type of film and the amount of light. Lenses on today’s commercial cameras are much bigger than pinholes and therefore admit more light in less time—hence the term snapshot. For now it will be enough to view images on the tissue or wax paper. Point your camera toward the Sun. (And if you do so during a solar eclipse, you’ll marvel at the clear crescents on your viewing screen.)