Cocabulary in english textbooks for Vietnamese upper-secondary students: A comparative analysis of reading

Abstract

In EFL countries where English is rarely practiced outside the classroom, textbooks have become the major input source for learners. To evaluate learners’ comprehension of textbooks, vocabulary has been proven to be the decisive factor. In Vietnam, multiple textbook series are available simultaneously for the same grade, thus, it is important to examine if their vocabulary is appropriate and equal for students to gain the equivalent outcome. This study aims to investigate and compare the lexis of reading passages in the eight latest series for Vietnamese 10th graders with 53,360 tokens in total. The study involved two phases. Phase 1 profiled the corpus with Nation’s (2017) British National Corpus/Corpus of Contemporary American English (BNC/COCA) wordlist using AntWordProfiler. The results revealed that 1,000, 2,000-3,000, and roughly 4,000 word families plus proper nouns, marginal words, transparent compounds, and acronyms were respectively needed for 85%, 95%, and 98% coverage, which would be challenging for the students’ reading comprehension. To gain further insight into lexical features of the textbook series, Phase 2 computed their lengths, lexical sophistication, and diversity with the assistance of TAALED 1.4.1. Pairwise comparisons by Jamovi 2.3.28 uncovered that the passages differ significantly in length yet insignificantly in lexical sophistication and diversity, meaning that these eight textbook series offered the students an equivalent range of advanced and rare words to cultivate their vocabulary through incidental learning. The eight series are concluded to be feasible for co-implementation and facilitative to vocabulary development despite not being optimized for independent learning. Still, the study calls for simplifying them to promote meaning-focused output. In the end, implications for exploiting and revising these textbooks are discussed.