The instruments used in this study were a vocabulary test and an achievement
test. The vocabulary test which is used as the pre-test in the study, included 56 words
which were selected from the English Book 3, a book which is taught in grade three
in guidance schools in Iran, one level above participants’ current level. The aim of
such a test was to cross out the words which are known for the participants of both
groups. The other instrument used in the study was an achievement test. It included
all the unknown words of both groups’ participants, which is 32 words. The test was
used as a post-test at the end of the study.