As more and more people look to institutions of informal education os places where science education occurs (Kimche, 1978; Tressell, 1980), increased attention has focused upon assessing learning in these out-of-school settings. In particular, instituions such as museums, nature centers, and zoos have devoted considerable efforts towards developing evaluation techniques. A multitude of procedures and approaches have been tired. These include questionnaires (Eason & Linn, 1976; Borun, 1977), empirical testing designs (Screven, 1974; Snider, Eason, & Friedman, 1979; Wright, 1980), and various