The vocabulary levels tests
The vocabulary level tests were adapted from the monolingual vocabulary level tests by Schmitt et al (2000). They were used in bilingual (English-Thai). Nation (2008) stated that this is a more valid measure for lower proficiency learners, because understanding a first language translation is much easier. These vocabulary level tests were used to find the subject‟s vocabulary size and to divide the subjects into two groups; high and low vocabulary size students. The tests consisted of items to test the knowledge of the vocabulary size of 2000, 3000, 5000, word level and Academic Word List.