An analysis of basal reading textbooks and their relationship to reading scores on the Iowa Test of Basic Skills

This study examines features of reading challenge in basal reading series in predominant use in the state of Iowa since 1955 in comparison with performance scores on the reading comprehension section of the Iowa Test of Basic Skills for fourth and sixth graders. It follows from studies by Dr. Jeanne Chall from Harvard University completed in 1977 and Dr. Donald Hayes and Dr. Loreen Wolfer from Cornell University completed in 1993 which both examined the scores of SAT takers in relationship to the textbooks they used. The data derived from an analysis of reading difficulty in fourth and sixth grade textbooks as measured by a readability index, vocabulary introduction, and picture ratios using descriptive statistics including a simple and multiple regression analysis. The findings support that a relationship does exist between textbook features and ITBS scores. At the fourth grade level, an inverse relationship exists between the number of new vocabulary words introduced and the obtained test score; a positive relationship was found between picture ratio increase and ITBS score increases. As measured by a reading index, when the textbooks increased slightly in difficulty, test scores rose for fourth graders. For sixth grade readers, findings were similar for picture ratios and new vocabulary introduction; but sixth grade scores increased when the reading challenge lessened as measured by a readability index. Publishers appeared to respond to demands by the market, reading researchers, and traditions of their own historical roots when adjusting text features to "match" student needs. Decrease in text challenge did not precede the decline in ITBS scores. Explanations are offered for these findings.