Word-formation knowledge and etymology, the study of word origins, have all the attributes of what educational psychologists term meaningful learning. Moreover, in the realm of foreign language learning, researchers try to find the best way of teaching languages. Considering these two points, a research was done to investigate the impact of word-formation knowledge on the lexicon and grammar of some freshmen students of Tehran University passing a course in General English.
After doing the statistical analyses on the students' scores at the end of the semestor, it was found that the knowledge of word formation had a positive impact on the performance of students in vocabulary and grammar.
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