Lexical difficulty and diversity of American elementary school reading textbooks: Changes over the past century

This paper reports the results of a detailed historical analysis of changes in lexical difficulty and diversity of the language used in elementary school reading textbooks widely adopted in the United States during the period 1905-2004. Applying a variety of analytical measures to a 5-million-word corpus of thirdgrade reading texts, we revisit the patterns of change in lexical complexity reported in previous research and examine the trends in more recent decades that have not yet been thoroughly explored. Our findings provide us with rich evidence for challenging some of the historical critiques of the American reading curriculum, and they have important implications for both educational history and policy.