عنوان مقاله [English]
This study aims to investigate the readability of Iranian English textbooks, Vision series 1-3, for high school. It focused on the reading sections of student books and workbooks. The texts were collected and fed into different readability tools such as Coh-metrix, and Flasch-Kincaid. The purpose was to evaluate the texts in terms of lexical and syntactic complexity as well as cohesion which included narrativity, syntactic simplicity, word concreteness, referential cohesion and deep cohesion. Each factor was able to increase or decrease the load of cohesion in the text. in addition, the output analysis managed to generally determine how difficult the passages were and what grade levels they suited. The findings revealed that there was some mismatch between the standard CEFR and NGSL wordlists and the number of words the learners study during their formal school language learning. Besides, the texts of the workbooks were to varying degrees incompatible with each other. Detailed examination uncovered some more features of each single text. Assessing the Iranian textbooks may be generalized to assist the international community such as teachers, material developers, and writers determine what might present difficulties to language learners and then take actions to improve their reading and writing skills .