英文摘要：English textbooks play an important role in English learning. Textbook readability and student reading comprehension are often strongly correlated. However, few studies have investigated the readability of textbooks used in junior and senior high schools in Taiwan. Thus, this study employed the Lexile Analyzer, a widely-used readability tool, to investigate the readability of six different sets of textbooks commonly used in junior and senior high schools. The readability scales of different sets of textbooks were analyzed and compared. In addition, the results were compared to American textbooks. The main findings of this study are: (1) the readability scales of different sets of textbooks, and even those within the same volume, often vary greatly, leading to significant readability gaps between volumes. (2) The significant readability gaps were found between volumes 1 and 2 as well as 2 and 3 in junior high school textbooks and between volumes 2 and 3 as well as 5 and 6 in senior high school textbooks. (3) The decisions concerned with using different sets of textbooks in junior and senior high schools might lead to reading difficulties. (4) The level of reading difficulty in some textbooks does not increase with grade levels.
