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In the past 20 years a number of alternative models of teaching have been developed for use in the science classroom. Many of these models were developed t o permit teachers t o implement more validly specific science curriculum projects. The "science inquiry model''-really a broad array of models-has been used t o characterize the teaching of effective BSCS, CHEMS, CBA, PSSC, H P 2 , and ISCS teachers. In essence, this global model calls for the teacher t o present science as an active investigatory process. Teachers present problematic events and through careful questioning and the timely introduction of information through readings, group or individual projects, laboratory experiences and the like, they encourage students t o become effective inquirers as well as learners of science content.There have also been a number of alternative models of teaching that have been implemented in other classrooms. The research and development efforts of Bruner, Ausubel, Suchman, Piaget, and even the philosophic stance of Carl Rogers, have catalyzed the development of various alternative models of teaching. Thus, the contemporary science educator faces a dilemma of selecting which of the many possible approaches to use with students in elementary and secondary science classes. A second dilemma exists for the science teacher educator who must select appropriate curricula for teacher education programs. This selection dilemma becomes more difficult as the range of alternatives continues to expand.A highly cogent description of the wide array of teaching models is presented by Joyce and Weil (1972). In their book, Models of Teaching, the authors define models of teaching as plans or patterns of strategies and tactics that the teacher can use t o guide instruction. Figure 1 summarizes IS of the models of teaching discussed by Joyce and Weil, and the lecture method, a less formally developed but certainly well-known science instructional method.The reader should note that most of the models can be directly identified with one or more of the well-known science curricula. Other models in the table have also found favor with science teachers, although the focus of some models is not inherently scientific. Even the Synectics model, while it may not be recognized by name by many science educators, is the

In any system of ether administration by inhalation, a percentage of ether vapor is added to the tidal respiratory air and is carried to the pulmonary alveoli during inspiration. On expiration, a part of the ether vapor is expired and wasted, the proportion of waste depending on the point in the respiratory tract to which the ether vapor has been delivered. The points of delivery of the ether vapor in inhalation anesthesia, arranged in order of their efficiency are: the bifurcation of the trachea, as in tracheal insufflation; the oropharynx, as in pharyngeal insufflation, and the nasal and oral orifices, as in the usual methods of anesthesia. ADVANTAGES OF PHARYNGEAL INSUFFLATION ANESTHESIAWhen compared with the delivery of ether vapor to other points in the respiratory tract, pharyngeal insufflation has manifest advantages. The introduction of the pharyngeal tube is a simple matter, takes little time and does not require a deep initial anesthesia. After the introduction of the tube, the surgeon has a clear field for operations on the face, head, neck, chest and upper air passages. No inhaler nor mask covers the mouth and nose. The operation is not hin¬ dered by proximity of the anes¬ thetist or of his appliances. The constant flow of air into the pharynx provides for the re¬ quirements of respiration, and permits covering the face with sheets and towels without inter¬ fering with the respiration. APPARATUSThe essentials for satisfac¬ tory pharyngeal insufflation are: an apparatus for delivering a current of air, capable of regulation up to 10 liters per minute; a vaporizer which will mix with the air current a constant percentage of ether vapor and which can be perfectly controlled as to the ether vapor percentage delivered, and nasal and oral tubes for delivering the ether vapor air mixture to the orophraynx.Means for providing the current of air for pharyn¬ geal insufflation are : an air pump actuated by an elec¬ tric motor, the speed of which is controlled by a delicate rheostat ; or a tank of compressed air controlled by a reducing valve ; or a foot pump. If no means for con¬ trolling the speed of the electric air pump is provided, the foot pump should be chosen, as the rate of flow of the air can be roughly controlled by the speed at which the foot pump is worked. The object of this apparatus is to keep the air in motion and not to produce positive pressure. ether vaporizer. Below, motor and air pump; bottle connected with suction apparatus.The mixture of ether vapor and air is formed by injecting liquid ether regularly, in small amounts, into the air current ; by atomizing or aspirating liquid ether into the air current, or by passing the air current over the surface of liquid ether in a container. In the last of these methods, which is the one most commonly used, the rate of vaporization depends on the tempera¬ ture of the liquid ether in the container. As evaporation goes on, the liquid ether constantly becomes colder, with resulting diminution in the rate of vaporization and in the anesthetic dosage. If...