english comparative forms in iranian textbooks compared to textbooks developed by native material developers

in the introductory stages of language learning, students are exposed to parative forms explicitly taught in their textbooks. as knoch (2004) mthis is accomplished by teaching the comparative form of the adjective generally directly followed by a than clause. this study aimed to compare between native and nonnative material developers with regard to the coverage of comparative forms. in doing so, two corpora of high school changes were developed and juxtaposed. the data were gathered books and converting them into computerized forms. the data by the frequency percentages of the forms and further examined and compared as well. the results revealed that there was a significant difference corpora with regard to the coverage of comparative forms.