English abstract
Textbooks are indispensable in most formal education settings. However, many teachers believe weaknesses in textbooks can result in ineffective learning and teaching. This research uses a corpus-based approach to identify issues related to vocabulary with a particular focus on English textbooks in use in Omani schools. WordSmith Tools and RANGE concordance software are used to analyze these textbooks. Findings indicate that there are irregularities in vocabulary loading and that the types, tokens, density and consistency ratio show inconsistencies. Moreover, in terms of the coverage of GSL and AWL word lists, the textbooks fall short of the ideal range of 95% to 98% coverage suggested by Nation (1990, 2001) .In fact, vocabulary from large percentages of the texts are not found in any of the essential word lists. The paper suggests recommendations for consistent analysis and guidance in analyzing textbooks in order to improve their quality in terms of vocabulary introduction and loading.
