The Type Organism Approach to Biology Instruction

Abstract

Though for some years the emphasis of biology teaching has been directed away from classification systems and taxonomic aims, still a considerable portion of the biology courses and textbooks is given to the task of broadening the learner's orientation and developing his organization of his knowledge of life forms. In most courses, the achievement of this somewhat taxonomic aim is attempted simultaneously with the achievement of the other aims of the course, through the use of the type-organism approach. This method, in which cursory examination or textbook contact with widely variant life forms is bolstered with intensive study of a single organism, is based on the assumption that type characters may be taught together efficiently as a single psychological grouping. It is the thesis of this article, first, that each type character is a psychological structure which requires care and attention for its accurate development, and second, that the extensive use of type organisms will hinder, rather than build, the effective type of taxonomic organization of life forms which is desired by the biology instructor. As an example of the problem at hand, consider the textbook approach to the unit or chapter on Arthropoda, traditionally exemplified by the crayfish. In biology courses as they are customarily reported by textbooks, work-books and the literature, such a unit is either preceded or followed by a discussion of several arthropods of widely variant types, some of which make an appeal to the student 's earlier experience. In some cases, collections of insects are prescribed or suggested; in others there is no definite program of observation. However, one can with safety say that nearly all such units include a detailed study of the crayfish, and that many, if not a majority of instructional units dealing with Arthropoda, make the crayfish and its study the central organizational structure. Fortunately, the high school mind does not perform spontaneously the careful scrutiny which was required to solve Agassiz's'legendary problem of the fish; if it did, inside the high school' classroom, one would daily be required to resolve the ancient taxonomic struggles between the splitters and the lumpers. Any reasonable examination will reveal the fact that the crayfish in adjacent dissecting pans are not alike; how then can the student-or the instructor-be sure that those who deal with the individual animals are facing the same creature? Each has its own size, shape, lengths of appendages, bumps, scars, and color, for each is'an individual in its own right, different from all others. However, we teachers are saved by the fact noted earlier-that the high school pupil commonly does not note the minutiae which distinguish individuals in species other than Homo sapiens, so that he sets up an i-ntellectual category-pigeonhole if you pleaselabels it crayfish and proceeds to dump all such creatures in it. The crayfish species idea comes easily; it is similar