Visual Education (Jan-Nov 1920)

Motion Pictures as an Educational Agency 19 the conclusions would have been quite different had he used the government film, which was prepared to teach soldiers how to read a topographical map. In the method of his experiment the chief variables to be taken into account are the time given to each exercise, the subjects to which the exercises were assigned, the method of presentation used, and the method of testing. The experimenter should plan to equate all factors except the one being investigated, and should in the interest of clearness report the precautions taken to secure such a limitation of variables. In number and distribution of subjects, in the arrangement of sections, and in the personnel of the teaching aids Mr. Lacy seems to have planned very well, but it is not so clear that he sufficiently equated the time for presentation for each of the types of exercises, or that his method of testing is of a sort to bring out the true effect of each mode of learning. Whether or not the presentation by story, by reading, and by moving pictures, extended over the same number of minutes is not clear from the description of the experiment. If, as Mr. Lacy states, the story-teller in narrating the story gave "a practically verbatim" reproduction of the text read by the reading section the time of presentation could hardly have been the same. The experiment gives no indication of the time used for the presentation by moving pictures. Neither is it clear how inequalities of reading rate were taken care of in the reading group, nor is it possible to tell whether or not pupils, who had furnished a single reading, were allowed to reread. It would, of course, have been possible to make the time of each method of presentation equal, but not for the presentation of identical data. If the time was not equal, then the conclusions are valid, only when amended to compare the effect of a single presentation, regardless of the time taken for such a presentation. Suppose, for example, that the time given to each presentation was as follows: motion pictures, twenty minutes; reading, thirty minutes, and oral presentation, forty minutes. The conclusions based upon the evidences offered by Mr. Lacy would be quite different. Important as are these possible differences in the time given to each type of presentation, they are not so significant in evaluating Mr Lacy s experiment as the effect of the type of test used. It is, of course, very difficult to arrange a set of questions which test with equal rigor what one has obtained from seeing a moving picture representing a certain story, as compared with what is obtained by reading the story itself. Assuming that the moving pictures have been accurately made and that the legends which accompany the pictures are ample and in harmony with the original text, it must be clear that one could ask a great number of questions which pupils who had not seen the picture could not answer. In a similar way, unless the pictures and the legend present all the data given in the story itself, it would be possible to ask the questions on the original material which could not be answered by those who had seen the picture. Mr. Lacy states that no data were called for in the questions that were not supplied in each form of presentation. Unfortunately, he does not give the questions, so that we are not able to judge their fairness and adequacy. Assuming, however, that precaution was taken to ask questions the answers to which could have been found in the picture, in the text and in the story, it must still be clear that the very