|Why using textbook written in Iran?|
The DehKhoda Textbooks for reading comprehension are by far the best print resource for language learning at the Intermediate Level that I have encountered.
First, the instruction in Persian is extraordinarily valuable, as 1) it forces students to engage with the language in earnest (English instructions can often give hints/ enable students who are not as sure in their knowledge of Persian to appear more knowledgeable) and 2) the majority of student experiences in the real world with Persian require intimate knowledge of how to follow instructions in Farsi (i.e. an entry-level analyst must first learn how to navigate Persian-language cordons of the internet before they can access body text).
Second, the book covers a wide array of topics that 1) force students both to learn new material and to form connections between words and usage and 2) expose students to new vocabulary.
Third, while the book's exercises may be a bit formulaic, the regular structure 1) entrenches a set of rigorous and high expectations in class and 2) forces students to think in a consistent and coherent manner about digesting reading material.