Reading Difficulty of Physics and Chemistry Textbooks

TEXTBOOK selection is an important but difficult task. The pri-mary reason for the difficulty is the lack of a foolproof method for evaluating textbooks. Methods now in use lack objectivity and are too often based on friendship with the salesman or on the attrac-tiveness of a cover (Mallinson, 1958). The factors for evaluating textbooks are manifold. However, among the most important is the factor of reading difficulty. Major (1955) has shown experimentally that decreasing reading difficulty increases the learning which takes place for students reading bi-ology material at both the high school and college levels. Marshall (1956) assumed that this would also be true for physics and chem-istry materials but concluded that the Flesch formula was not ap-propriate for determining or for modifying reading difficulty in these areas. He recommended that educators discontinue using this and other reading formulae for predicting the difficulty of physics and chemistry materials unless their use has been validated experi-mentally. To date this validation has not been done satisfactorily for any formula in the literature. This study had two objectives. The first was to determine the relative reading difficulty of physics and chemistry textbooks in use in Minnesota public schools. This objective will be considered in Part I of this study. The second objective, which will be con-sidered in Part II, was to compute regression equations which would be valid for predicting the reading difficulty of physics and chemistry textbooks.