This study investigated the effects of exposure frequency, depth of processing, and activity repetition types on vocabulary learning. In total, 78 South Korean fifth-grade students were divided into four conditions. Students in each condition were asked to read a passage with four of the eight target words (exposure: four times) and the other four words (exposure: once) for three days, and to perform the vocabulary activities assigned to each condition. According to the results, exposure frequency and activity repetition type had significant effects on vocabulary learning. Activity repetition type also had a significant interaction effect with exposure frequency and depth of processing. Notably, presenting a word 12 times (4x3) in reading intervals had a more positive impact on vocabulary learning than presenting it three times (1x3), particularly when different vocabulary activities were repeated. Meanwhile, when the same activity was repeated, an activity with a higher depth of processing was more effective for vocabulary learning.

The primary purpose of this study was to examine prominent features of frequency in the new vocabulary of the middle school English textbooks based on the 2007 revised national curriculum and thereby to provide meaningful data to be compared with those on the 2009 revised national curriculum. This study used an online software (Vocabprofile) to divide words into four categories by frequency: K1 (1-1,000), K2 (1,001-2,000), AWL (Academic Words List), and Off-List Words (the remainder). Salient features discovered from the frequency-based categorization of words in textbooks by grades or publishers were further examined for pedagogical implications regarding textbook writing and curriculum revisions in the future. The analysis has revealed the following results. K1 words accounted for the most among the words presented in English textbooks, reflecting the significance of the high-frequency words in L2 learning. The number of other words showed a steady increase as the grade gets higher. Finally, most textbooks presented multi-words as new vocabulary, which indicates the importance of idioms or collocations. The vocabulary analysis by frequency could be of use to textbook evaluation, considering the growing importance of frequency-based vocabulary teaching.