A Corpus-based Comparative Study Of College English Coursebooks

Coursebooks have been playing an important role in the teaching process. Coursebook evaluation provides a scientific basis for the selection of teaching materials, adaptation of existing materials or the supplementary materials and teachers'decisions on adjustment in teaching practice. Currently, coursebook evaluations which have been influenced by several foreign linguistic and second language learning theories and checklists both at home and abroad mainly based on subjective assessment and experts'personal experience, which lead to non-objective evaluation because of overwhelming qualitative analysis and lacking of quantitative indications. Richards (2001) analyzed the characteristics of qualitative analysis and quantitative assessment respectively and pointed out that both of them were necessary and complementary and for different purposes. Qian (1995: 19) pointed out that the evaluations of coursebook in whether the language (structure, vocabulary, genre features) are in consistent with the College English Curriculum Requirements, whether the frequency, grading and sequencing appropriate are difficult to complete manually, therefore, how to use computers to complete language evaluation work is an urgent project to resolve.This study bases on self-built"College English Coursebook Corpus", using Cunningsworth (2002) theories and its adapted checklist, taking College English Curriculum Requirements (2007) (Requirements) as criterion, with a combination of quantitative and qualitative approach to explore four sets of widespread college English coursebooks from the following three aspects:1. Relating to language content: How much vocabulary is taught? What is principled basis for selection of vocabulary? Is vocabulary presented in a structured, purposeful way? How many collocations?2. Concerning material selection: Is any predominants as the basis of selection of content? i.e. structure, functions, situations, topics? Are real topics included in the coursebook? If so, how varied are they? Is genre presented widely? Will the coursebook contribute to develop learner's genre sense?3. Regarding to grading and sequencing: Is there any evident basis for the sequencing—eg. functional organization, situational organization, organiazation according to topic? Will the sequencing based on complexity, learnability, usefulness, etc? If so, how well are they balanced? Are language items adequately recycled? Are the grading and sequencing suitable for the learners?By comparing and analysing the statistics, this paper finds: (1) To some degree, there is a gap between the learning resources provided by four sets of coursebooks and the requirements set by Requirements. The research findings indicate that some of these coursebooks do not meet learners'needs, requirements and teachers'expectations, and the situation is impressing. The coverage of basic level vocabulary, the coursebook of highest coverage is New Horizon College English (NHCE) (88.5%), College English (New) (CE) (74.76%) and Twenty-first Century College English (TCCE) (67.52%) are inferior to NHCE, in the third place, Experiencing English (EE) (61.58%) relatively covers the least vocabulary of Requirements. NHCE and CE have a higher coverage, while for TCCE and EE, the coverage of basic level vocabulary (61.58%-67.52%) are far from the recommendation vocabulary of Requirements. There is almost 40% words of basic level wordlist which need to be contained in TCCE and EE. Coursebook should ideally include at least basic level vocabulary, if properly selected or managed, a set of coursebook can contribute to the goal of vocabulary learning for the objective of graduating from university. (2) According to learners'cognitive rules and progressive principle, the sequencing and grading of four sets of coursebook, for example, the compilation of grading and recycling of new items, need to be adjusted and improved. (3) In material selection, there is wide range of topics in four sets of coursebooks but not for genres, which is helpful to extend learners'horizon of thinking and arouse motivation, but not useful for developing learners'genre sense which is equally important for writing or future career. The findings above may be of some help for coursebook compiler to edit and learners to choose a set of coursebooks which are accurate in positioning, advanced in teaching concepts, consistent with second language acquisition rules and characteristics of learners'cognition, various in themes and genres.The study also proposes a corpus-based empirical study approach which may help teachers and learners to evaluate coursebooks objectively. With rapid development of modern computer, corpus provides the possibilities of doing the research easily. The corpus-based approach will simplify the evaluation process and provide necessary supplementaries, some properly criteria of quantitative or more operational evaluation to solve the problems existed in various evaluation systems. Thus a new approach, based on the general second language acquisition theories and taking English textbook corpus as a checking tool, provides new thoughts to the English coursebook evaluation.