Describes a method using lap-dissolve slide techniques with two or more slide projectors focused on a single screen for presenting visual effects that show structural features in extended arrays of atoms, or ions involving up to several hundred atoms. Presents an outline of an introduction to the structures of crystalline solids. (CS)

Advantages and disadvantages of using multi-image or lap-dissolve (LD) slide techniques in large lecture sections are discussed. Production, use, and evaluation of LD programs are also discussed. Indicates that these programs are an effective way of improving instruction on visually oriented topics. (JN)