作为英语语言的基本要素之一，词汇是学习者培养听、说、读、写四种基本技能的根本保障，充足的词汇量更是交际沟通的基础。然而，由于英语单词量巨大，记忆负担较重，中学生对词汇学习产生无力感甚至抵触情绪。研究已发现，语言中存在着大量对词汇学习有显著帮助的词块。因此，探究在中学英语课堂中使用词块教学法培养学生词汇能力的有效策略是值得关注的问题。
为了贴近真实的词汇教学情景，本研究关注基于课本语篇的词汇教学，也称为“语篇词块”教学法，以四川L中学八年级的三位老师以及各自所教的共六个班级为案例进行个案研究。本研究主要采用课堂观察、访谈、问卷、实物收集的研究方法进行数据收集和分析，主要回答以下三个核心研究问题：1）教师如何在课堂中开展语篇词块教学法来进行词汇教学？2）语篇词块教学法对学生的词汇能力产生了何种影响？3）语篇词块教学法是如何影响学生的词汇能力的？。
本研究共有以下三个研究发现。第一，以访谈和课堂观察为主要工具，研究者发现案例教师以历时逻辑实施语篇词块教学法，课前精心选择教学词块并设立清晰词汇教学目标，课中采用一系列教学策略培养学生词块意识，以及课后利用作业和听写扩充学生词块输入和锻炼词块产出能力。第二，通过问卷和访谈结果分析，学生词汇能力所涵盖的三方面均得到了显著提高，词汇学习态度发生积极转变。通过语篇词块教学法，学生表示词汇记忆更加高效，在输入性学习活动中能识别更多词汇，词汇广度有效扩大；学生对词汇知识了解更全面细致，在词汇能力的深度方面表现出提升；在词汇能力的自主性方面，学生表现出语言产出过程中流利性和准确性的明显提升。第三，以访谈为主要工具，研究者探索了语篇词块教学法是如何有效促进学生的词汇能力的，发现以下三条重要影响途径：词块意识的建立对记忆加工的有效帮助；真实语言材料输入对学生交际能力的培养；学习词块而不是单词是语言输出时流利性和准确性的保障。 
为了帮助一线教师在教学实践中更清晰地使用语篇词块教学法有效进行词汇教学，研究者还依照课前、课中和课后时间顺序，提出了一系列教学实施策略。
由于时间和条件有限，本项研究仍存在某些不足之处，如研究对象应更具有普适性、研究方法适用性仍需改进等，研究者也会在日后的教学实践中进一步完善研究。但总体来说，研究较为圆满地回答了提出的研究问题，希望可以为初中英语教师有效培养学生词汇能力提供有益的实践参照和建议，也能给予未来相关主题研究的研究者一些思考和启示。

As one of the basic elements of the English language, vocabulary is the fundamental guarantee for cultivating the four basic language skills. However, due to the massive amount of English vocabulary, the students develop a sense of powerlessness or even resistance to vocabulary learning. Previous studies have found that numerous lexical chunks existing in a language exert positive influence on vocabulary learning. Therefore, it is worth paying attention to explore the effective strategies of implementing lexical approach to improving students’ vocabulary competence in middle school English classes.
To fit into real teaching scenarios, this study focuses on vocabulary teaching based on discourses in English textbooks, namely, discourse-based lexical approach, and conducts a case study on three teachers in grade eight from L Middle School in Sichuan and six classes they teach. This study adopts classroom observation, interviews, questionnaires, real materials collection for data collection and analysis. Three core research questions are answered: 1) How does the teacher conduct discourse-based lexical approach in vocabulary teaching? 2) What effects can discourse-based lexical approach have on students’ vocabulary competence? 3) How does discourse-based lexical approach affect students’ vocabulary competence?.
There are three primary findings in this study. First, through interviews and classroom observation, the researcher found that the teachers in this case implement discourse-based lexical approach in a chronological order. They carefully select lexical chunks to be presented and set clear vocabulary teaching objectives before class, adopt a series of teaching strategies to cultivate students’ chunk awareness during the class, and design homework and dictations to expand students’ language input and output after class. Secondly, the results of the questionnaires and the interviews showed that students’ vocabulary competence has noticeably improved in all of the three aspects and students’ attitudes towards vocabulary learning has witnessed positive changes. Through discourse-based lexical approach, students memorize vocabulary with higher efficiency and can recognize more vocabulary in receptive learning activities, which means their breadth aspect has been expanded; students demonstrate a more comprehensive grasp of vocabulary knowledge, which reflects their enhancement in depth aspect; as for autonomy aspect, students perform language output activities with advancing fluency and precision. Thirdly, through interviews, the researcher explored how discourse-based lexical approach successfully affects students’ vocabulary competence. The following three significant channels deserves attention: the development of chunk awareness can effectively help memory processing; the input of authentic language materials can nurture students ’real communication ability; learning chunks rather than single words can ensure the fluency and precision in language output.
Moreover, in order to help front-line teachers practice discourse-based lexical approach more effectively, the researcher puts forward some feasible implementing strategies before class, during class and after class.
Meanwhile, due to limited time and condition, this study has some shortcomings. Research participants should be more representative and generalized, and the research methodology should be more diversified and applicable. The researcher will continue exploring and refining this research in future career. However, on the whole, the research has satisfactorily answered the research questions, hoping to provide useful and practical references and suggestions for middle school English teachers to effectively cultivate students’ vocabulary competence, and offer some inspiration to researchers on related topics in the future.