In the selection and evaluation of instructional material, a teacher of medical students has to take into consideration many variables. First of all, it should be mentioned that every applied tool has its advantages and disadvantages, and in such a way, it may not be considered better than another. The key factor that predetermines the effectiveness of the educational process is the teacher’s “knowledge of the diversity of the instructional tools.” It may be distinguished three major variables in choosing and developing instructional materials. As distinguished by Bastable, these variables are: “characteristics of the learner, characteristics of the media, and characteristics of the task.”
While defining the characteristics of the learner, Bastable states that “man variables are known to influence learning.” In order to choose the most appropriate media, it is of key importance for a health instructor to know his audience, its demands, and abilities. The existing variety of printed and audiovisual media provides many possibilities for enhancing different methods of teaching and means of their realization. Printed materials are considered to be the most abundant form of distribution of information. At the same time, non-printed materials provide a wide range of audio and video opportunities. Bastable states that no one form can be considered the most effective, and a teacher has to be flexible in choosing a multimedia approach. Characteristics of the task mean the identification of the learning domain and its cognitive and psychomotor aspects.