investigating the effect of graphic organizer strategy instruction on iranian vocabulary learning ability

this study was conducted to investigate the effect of graphic organizer vocabulary instruction on iranian vocabulary learning ability. for this purpose, 80 learners of english participated in this study. all the groups were taught the same textbooks. oxford placement test was used in order to get homogenized groups of participants. they were also given a vocabulary pretest, to measure the learners’ initial knowledge of the target words. the treatment procedure took ten sessions and thirty-minute each session. during each session, the students in the experimental groups were presented with 10 new words' pictures on a4 papers. in the control groups, the learners got the list of the new vocabulary with the synonyms and definition. finally, at the end of the course all the groups sat for the posttest of lexical knowledge. then the statistical analysis was run through independent-sample t-test. the results showed that the experimental group which was taught with graphic organizers outperformed the control group which was taught with a traditional method