A Study Of Effects Of The Project-based Learning Teaching Method On Academic English Vocabulary Diversity Of Non-english Major Postgraduates

With the internationalization of higher education,the academic exchange at home and abroad has become increasingly frequent.Hence the academic English writing capabilities of postgraduates are in urgent need to be sharpened for better communication,especially the application of academic vocabulary.The project-based learning teaching method(PBL teaching method for short)has been widely applied in foreign language teaching while scarcely adopted in academic English writing teaching.With an application of the PBL teaching method to academic English writing teaching,this study,taking reporting verbs for example,aims to explore the effects of the PBL teaching method on lexical diversity of academic English vocabulary of postgraduates in order to provide some inspirations for the future academic English teaching.Taking reporting verbs for example,this study conducted an empirical research and a retrospective interview proceeded in a university to explore the effects of time and teaching method on the academic English vocabulary diversity of non-English major postgraduates,and further probe into the interaction effects of time and teaching method on postgraduates' academic English vocabulary diversity.Based on the previous studies,the academic English vocabulary diversity was measured from two dimensions: lexical density and lexical complexity.Two separate classes consisting of 60 non-English major postgraduates participated in the experiment,one of which worked as the experimental group,taught under the guidance of the PBL teaching method,and the other as the control group,guided by the traditional teaching method.During the experimental period,all participants were required to attend three tests,namely writing three topic-given essays,in the beginning,in the middle and in the end of the term respectively.And then the essays collected were processed by Antconc 3.0,a freeware corpus analysis toolkit for text analysis and in the end analyzed by SPSS 22.0.Results of the present study show that: 1)The PBL teaching method could enhance the lexical diversity of postgraduates to a certain degree and the longer the time was,the more obvious the growth would be.To be specific,participants in the experimentalgroup achieved significant progress in terms of lexical complexity over time while a relatively gradual increase as to lexical density.In addition,the growth of lexical diversity in the later period was more notable than that in the earlier period.2)It was found that the teaching method effect on improving postgraduates' academic vocabulary diversity was insignificant.In the earlier period of the experiment,the lexical diversity of participants in the experimental group was slightly lower than that of the control group while in the middle and later periods,that of both groups was comparable and no significant increase was discovered.3)Upon the interaction effects of time and teaching method,the PBL teaching method,compared with the traditional teaching method,was more effective in improving the lexical diversity of postgraduates,especially in terms of lexical density.In detail,the lexical density of postgraduates' was elevated prominently while the lexical complexity increased insignificantly.Besides,through the retrospective interview,the present study found that under the guidance of the PBL teaching method,participants in the experimental group achieved a larger input of academic vocabulary and realized an effective output in the writing.However,they still had difficulties in applying low-frequency words.Meanwhile,the PBL teaching method was also found beneficial in cultivating postgraduates' abilities such as critical thinking ability,problem-solving ability and communication skills by means of self-learning.Implications of this study are as follows: firstly,more research directions concerning the vocabulary teaching can be explored in the future on the basis of the application of the PBL teaching method to the academic vocabulary teaching.Secondly,some experiences can be derived from this study on how to design and conduct an experiment to investigate the effects of the PBL teaching method in a certain field.Finally,the writing teachers may be enlightened by the present study in the way of shifting the role of teaching into guiding students in exploiting their writing potential to the fullest by integrating cooperative learning with autonomous learning.