Vocabulary Coverage in a High School Vietnamese EFL Textbook: A Corpus-based Preliminary Investigation

In the context of English as a foreign language (EFL) teaching, textbooks play crucial role in classroom primary source lexical input for learners. Thus, it is essential that can sufficiently facilitate learners their overall comprehension and vocabulary learning, especially with most frequent words English. The study examined load locally-published EFL textbook Vietnam high school students focusing on coverage relation to 95% 98% thresholds text high-frequency word families textbook. To fulfil these objectives, frequency-based analysis using Vocabprofilers https://www.lextutor.ca/ website was conducted 41,137-word corpus. It revealed need have size 3,000 5,000-word reach whole textbook, which would be too challenging Vietnamese students. Moreover, found not represent second 1,000-word list very well appearance just over half families. These findings highlight teachers adapting more effective learning general materials.