evaluation of english textbooks taught in iranian secondary high schools from the processability theory perspective

Pienemann’s process ability (pt) theory is on the assumption that there is a limit on the human’s short-term memory and processing capacity. on the one hand, it means that those language structures which need higher processing should only be produced in the later stages of second language acquisition. on the other hand, it means that what is presented to second language learners has to be in line with their current level of proficiency. the present paper was an attempt to see if the english textbooks (vision 1, 2, 3) taught in iranian secondary high schools follow the developmental stages offered by pt. it also aimed to see if there was a smooth pedagogical progression from the first grade to the third grade in these textbooks. the findings showed that they only were successful at stage 1 of pt. in other words, they were more concerned with presenting words and phrases but when it came to other stages of the pt three major deviations were noticed: a) the early presentation of question forms before svo structure is well-established, b) mixing the stages of pt, and c) omission of some intermediate stages. with regard to the second purpose, no smooth progression was seen from grade one to grade three. for example, while vision 1 introduces subordinate clauses, surprisingly, a year later vision 2 presents countable/uncountable words like “some, many, a few, a little...” which, according to pt, are a lot easier to process than complex sentences containing subordinate clauses.