Lexical Demands and Features of English Textbooks for Vietnamese 10th Graders: An In-depth Comparison of Listening Sections

English textbooks are the most pivotal learning materials in the EFL context. However, in Vietnam, English textbooks for general education are randomized by schools, which arouses a problem of whether they are equivalent for students to gain the same proficiency. This study attempts to report the differences in lexical demands and features, including length, sophistication, and diversity, of these textbooks. To this end, the researchers compiled a corpus of 54,566 tokens extracted from their listening transcripts. Results profiled by AntwordProfiler showed that 1,000, 2,000 to 3,000, and 3,000 to 4,000 word families in the BNC/COCA wordlist plus four supplementary lists of proper nouns (PNs), marginal words (MWs), transparent compounds (TCs), and acronyms were necessary to comprehend 85%, 95%, and 98% of listening in all the textbooks, correspondingly. Moreover, the results of pairwise comparisons run by Jamovi indicated significant differences in text length and lexical diversity between the textbooks but not in sophistication. In short, these grade-10 textbooks could support students in learning English vocabulary although they impede students from using them randomly. Hence, the study heightens the roles of teachers in the classroom and paves the way for researchers who are fond of vocabulary and English textbooks.