An evaluation of the readability of five developmental reading series

The purpose of this study was to evaluate five developmental reading series as to the readability scores, grade levels of new words introduced, and the reinforcement of the new words. The readability scores were calculated by the Spache Readability Formula and the DaleChall Formula. The new words introduced in the series were listed on the Worksheet for Analysis of Instructional Materials Beyond Readability Scales (Schindler, 1980) and then matched with A Functional Basic Word List for Special Pupils (Tudyman and Groelle, 1963) to find the actual grade levels. Reinforcements of new words were tabulated also on the worksheet by Schindler.

From these instruments of comprehensive evaluation, one developmental reading series showed a direct relationship between graded new words and the frequency of reinforcements with the actual readability versus the publisher's estimated readability. The other four developmental series showed a relationship influenced by some other factor of readability. From these findings, the other factors that are thought to influence readability have limited the relationship between readability scores and the new words introduced with frequency of reinforcement.