Frequent quizzes followed by feedback on students’ strengths and weaknesses may enhance learning. Hence, the possible effect of weekly quizzes on language learning might be of interest in Iranian EFL context, especially in high schools. In order to understand the importance of weekly short quizzes, 88 students from four classes of high school second graders were selected through available sampling to form the experimental and control groups. The treatment went for twelve weeks during which the experimental group received 10 weekly quizzes while the control group did not have any quizzes. The study was carried out through a pretest- posttest- delayed posttest control- experimental intact groups. The results, analysed through Mixed Models ANOVA, revealed that both within and between group’s differences were in favour of the experimental group. It is safe to claim that weekly quizzes improve students’ performance on vocabulary and the effect of the treatment is durable.
