英语论文网

re many problems with the use of vocabulary injunior high school students'writing,such as failure to express the right meaning ofsentences,the shortage of vocabulary,and many lexical errors in their writing.Tosome extent,these problems have affected the students'writing performance andhindered the development of their writing abilities.

Chapter Two Literature Review

2.1 Key Concepts

This section focuses on the relevant concepts involved in this research,includingthe definition of PBL,the definition of English writing,and the definition of lexicalrichness in English writing.

2.1.1 Project-based learning(PBL)

PBL is a systematic teaching method(Buck Institute for Education,2008;Holubova,2008;Panasan,2010;Liu,2020;Yang,2021).

PBL has multiple definitions.Most definitions are based on teaching methods andteaching strategies.The definition of standardized PBL defined by Buck Institute forEducation(2010)is quite representative,that is,PBL is a systematic teaching methodthat aims to urge students to acquire knowledge and skills through extensive andin-depth exploration of complex and real problems and well-designed products andtasks.Solomon(2003)thought that PBL means that students solve real andchallenging problems in the form of groups,and the problems are based on coursesand usually involve interdisciplinary content.Learners can decide for themselves howto solve problems and what activities to carry out.They can obtain project-relatedinformation through various resource channels,analyze and synthesize the obtainedinformation,and derive knowledge in the process.Such learning has intrinsic valuebecause it involves things related to the real world and cultivates students'cooperationand reflection skills.At the end of the project,the students present the new knowledge they have acquired,and the assessor evaluates the degree of knowledge acquisitionand the effect of communication.In the whole process,teachers do not directly guideand manage students'learning but play the role of guider and advisor.Bell(2010)defined PBL as a way to drive students to learn with the help of teachers.Studentspursue knowledge by asking questions about things they are interested in.The projectoriginated from inquiry,which is the key strategy to cultivate students'independentlearning and independent thinking.

2.2 Previous Studies on Lexical Richness

At present,the previous studies on the lexical richness of English writing at homeand abroad mainly focus on the development characteristics of L2 learners'lexicalrichness in writing,the relationship between lexical richness and L2 writing quality,the measures of lexical richness,and other studies related to the lexical richness inwriting.This part elaborates on these four perspectives.

2.2.1 Studies on the development characteristics of L2 learners'lexical richness

The development characteristics of lexical richness in English writing amongstudents have been a hot research topic of concern for scholars both domestically andinternationally.Laufer(1994)carried out a comprehensive study on the compositionsproduced by 48 first-year college English majors in Israel during one academic year.The study revealed that while the lexical sophistication in their writing significantlyimproved,their lexical variation did not show a noticeable improvement.In 1998,thisscholar conducted a sub本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。