Two key factors affecting the success of non-major science courses are students' perceptions of topic difficulty and interest. An attitudinal survey administered to 300 college students, after completion of a college science course, evaluated their attitudes toward a geology curriculum. Using a Likert type scale students rated their level of interest and the degree of difficulty for 15 specific class components. Some of the topics investigated were: (1) differences between rocks and minerals; (2) metamorphic rock formation; (3) reading a topographic map; and (4) the role wind plays in erosion. Analysis of the results analyzed by the stochastic Rasch model revealed that although some correlation exists between "difficulty" and "least interesting" topic, there were some topics viewed as both difficult and interesting. Three implications for earth science courses were provided: (1) incorporate the techniques (pictures, real life experiences) which interest students in topics that they are less interested in; (2) develop new methods to teach students to use topographic maps; and (3) present sedimentary rock formation after igneous and metamorphic processes. The development of geology curricula from an approach that considers students' interest and the science topics' level of difficulty can aid educators in making necessary revisions in geology courses. (ZWH)