Linguistic complexity in EFL teaching materials: A grade level comparison of EFL textbooks in Turkey

The present study aimed to measure text difficulty of the L2 English textbooks used in the state schools in Turkey in terms of their readability and linguistic complexity (i.e., syntactic and lexical complexity). It further compared two locally published textbooks to two internationally published comparable textbooks to check the similarity of the texts in terms of their readability and linguistic complexity. A corpus of 765 texts, more specifically 329 reading texts and 436 listening texts, were extracted from one series of L2 English textbooks currently used in Turkish state schools from Grade 2 to 12 and two internationally published textbooks (i.e., Interchange3 and Passages1). Overall, 3 readability formulas, 12 syntactic complexity measures and 8 measures of lexical complexity were used to analyze the texts through three online computational tools (i.e., Coh-Metrix, L2 Syntactic Complexity Analyzer (L2SCA) and Lexical Complexity Analyzer (LCA)). The results indicated that linguistic complexity of both reading and listening texts showed a gradual increase along with the increase in the grade levels while, with some exceptions, many measures stabilized across adjacent grades or clusters of grade levels. Although the results of the comparisons among locally and internationally published textbooks were mixed, they supported the findings of the comparisons of the textbooks used in state schools. The results of the study may have implications for the design and evaluation of L2 English teaching materials.