The Effects of Thematic Progression in Improving Coherence and Cohesion in EFL Writing

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Introduction
Academic writing could be considered the most challenging skills as it requires to meet a number of criteria, for example: content (thesis statement, main ideas, supporting ideas, etc.), organization (introduction, sequence of ideas, etc.), discourse (discourse markers, cohesion, etc.) and vocabulary (Brown, 2000).Even advanced students who have good command of grammatical rules and vocabulary may still produce essays that sound unnatural and ineffective to native instructors (Kaplan, 1966).In other words, grammatical and lexical error-free texts may still violate native speaker expectations at the discourse level, making them struggle to interpret the information.This problem even deteriorates in some countries where the grammar translation teaching method (GTM) is prevalent in language teaching context because GTM mainly focuses on sentence-level skills (syntactic rules and lexis), disregarding properties that contribute to coherence and cohesion.
From the view of functional grammar by Halliday (1985), a coherent and cohesive piece of writing necessitates the consciousness of thematic progression for the reason that thematic progression could upgrade writing skills, not at sentence-level but discourse-level.The important role of Theme-Rheme structure in the construction of an effective discourse has been proved by many studies so far.Following this line, this current study was conducted to clarify the extent of improvement in terms of coherence and cohesion that thematic progression could do to the writing skills of Vietnamese students, with the hope of elevating and popularizing the theory in language training.Moreover, the study is also aimed at identifying the most common theme-rheme problems and learners' difficulties when they employ thematic progression.

Theme and Rheme
According to Halliday (1985), theme is the element that serves as the point of departure of the message and what the speaker/writer has in mind to start.The remainder of the message is called the rheme.In the theme-rheme relation, the theme sets the background for the rheme -the following information.
In classifying themes, Nunan (1999) termed three types of theme, namely Topical theme, Textual theme and Interpersonal Theme.Topical theme is obligatory in each clause, while textual and interpersonal theme is optional.
Topical themes are regarded as the starting point of the core message in the discourse.They could take the form of a nominal group (he, the boy), a prepositional phrase (with the development of the Internet), an adverbial group (in the garden, by the middle of the 20 th century), or even a dependent clause (if the food tax is raised).
Textual themes link a clause with the others in a discourse; they could be presented by a set of words that marks a new move of idea or information (firstly, to begin with, the reason is), structural elements/ linking items (and, for, but, therefore, etc.).
Interpersonal themes express the feeling and attitudes of the writers or speakers; they are the modal/comment adjunct (probably, evidently, honestly); they also can be realized in a separate clause that reveals the writers' or speakers' feelings (it is desirable that).Nunan (1999: pp.46-47)For example: Therefore, possibly telling the truth is the best option.
Textual Interpersonal Topical Rheme Theme

Theme-rheme Problems
The problems of using inappropriate theme and rheme are common among EFL learners.There are five main mistakes in using theme and rheme that EFL learners usually make: brand new theme, double rheme, empty rheme (Bloor & Bloor, 1992), overuse of constant theme pattern, and confusing selection of textual theme (Arunsirot, 2013).
The problem of a brand new theme occurs when the brand new information is put in the theme position (Bloor & Bloor, 1992); for example, "There are some drawbacks that can negatively affect the host country (1).People in ethnic minorities might suffer from discriminatory behaviors when they come to big and modern cities. (2)".The theme of the second unit is "people in ethnic minorities", which is relatively new, and it does not go with the expectation raised by the previous sentence.Because of this, readers would find the text difficult to follow, and the communication purpose can be broken down at the sentence level (Wang, 2007).
The problem of double rheme refers to a sentence including two rhemes with one of the rheme not mentioned previously (Bloor & Bloor, 1992).For example, "Organizing an international event could attract a lot of tourists to the host country, but this comes with a catch (1).Because of the dense number of tourists, means of transportation would need to work intensively and optimizing to save fossil fuels (2).In this instance, there are two rheme: the first rheme is "means of transportation would need to work intensively", the second rheme is "(means of transportation) would need optimizing to save fossil fuels".It is noticeable that the information in the second rheme has not been mentioned in the context, and it does not go well with the flow of information (Wang, 2007).
The problem of empty rheme happens when the writer fails to provide new information in rheme or the information does not have enough elaboration (Bloor & Bloor, 1992).For example, "Hosting an international sports event can cause many problems for citizens (1).These problems can deprive many benefits from them(2)."The rheme "cause many problems" is considered empty since it is too general, failing to clarify the argument.As a result, the reader may not comprehend exactly what the writer is trying to convey (Wang, 2007).
According to Arunsirot (2013), the problem of overusing constant theme patterns occurs when the writer puts the same theme over several clauses.In this case, the writer tends to focus more on the theme instead of developing the rheme.For example, "(1) Hosting an international event can cause many problems for citizens.(2) It could also pollute the atmosphere, (3) or it could lead to a shortage of fossil fuels."Having the same theme in a string of sentences could create a repetitive and stagnant text flow (Nguyen & Nguyen, 2020).This effect results in shallow arguments which cannot persuade the reader as well as accomplish the writer's purposes.
The problem of confusing selection of textual themes occurs when the writer mistakenly selects the textual theme.This problem will lead to unconnected (or incoherent) clauses.For example: "(1) Hosting an international event can cause many problems for citizens such as pollution, and traffic congestion.(2) However, the government should consider carefully before deciding to host this event."The conjunctive adverb (textual theme) does not function properly; to be more specific, this word fails to express the existing relationship between two sentences; therefore, the flow of information is disrupted (Arunsirot, 2013).In some worse cases, having a wrong textual theme could be a fault signpost for the reader; as a result, their readability could be hindered.

Thematic Progression
The working definition of thematic progression in this current research is from Eggins; the researcher claims that thematic progression is the exchange of information between consecutive theme-rheme pairings in a text (Eggins, 2004).Thematic progression is a chain of themes and rhemes, connecting with the themes or rhemes in the other clauses in semantic or referential ways.Those theme-rheme connections among sentences build patterns (Danes, 1974).
According to Danes, there are three main patterns, namely Rheme-Theme, Repeated-Theme and New-Theme.However, this system of theme-rheme patterns fail to cover some cases (Dubois, 1987) such as the pattern of repeating rheme as well as unmotivated theme (Ventola & Mauranen, 1991).Therefore, Ho (2011) has referred to a number of theme-rheme studies to complement the system of thematic patterns with three more patterns, namely Extended theme-theme, Extended rheme-theme and Unmotivated new theme.

TT
The topical theme of the previous unit is reused to be the topical theme in the next one.
The host country could gain many benefits from tourists and sports fans.In addition, this country also has the chance to promote its image to the world via different media platforms.

RT
A part of the rheme in the previous unit is reused to be the topical theme of the next unit.
The host country could gain many benefits from tourists and sports fans.Those people are willing to spend a huge amount of money to have a ticket to their favorite match.

ETT
The topical theme of the previous unit is reused to be the topical theme of the following unit.However, this topical theme is not reused immediately but after one or more intervening units.
The host country could gain many benefits from tourists and sports fans.Those people are willing to spend a huge amount of money to have a ticket to their favorite match.Therefore, the host country could earn a lucrative profit.

ERT
A part of the rheme in the previous unit is reused to be the topical theme of the following unit.However, this part of the rheme is not reused immediately but after one or more intervening units.
The host country could gain many benefits from tourists and sports fans.In addition, a number of conglomerates can also get a larger profit from this event.Tourists and sports fans always willingly spend a lot of money to have a ticket to their favorite match.

MNT
A totally new theme, unrelated to the previous theme and rheme.However, this new theme still remains in the link with the idea of the paragraph.
The host country could gain many benefits from tourists and sports fans.People in the host country have many chances to start small businesses.

UMT
A totally new theme, unrelated to the previous theme and rheme.In addition, this new theme is not logically and semantically linked with the idea of the paragraph.
The host country could gain many benefits from tourists and sports fans.Parents can take their children to schools

Coherence and Cohesion
In general, coherence is defined as the text's semantic unity, which ties the entire text together as a single unit of meaning (Knoch, 2007).Coherent writing has a consistent flow of ideas, with one sentence logically following the next without deviating from the central theme (De Beaugrande & Dressler, 1981).In contrast, an incoherent text does not transmit good sense or meaning, as it does not have logical progression and connection through paragraphs and the whole text.
Cohesion is considered a text-forming device that enables the writers (or speakers) to establish the relationships across sentences and tie these sentences in a text together (Nunan, 1999).Also, Halliday (1976) claimed that linguistic cues join the text together; these cues are considered cohesive devices or textual links.These textual links could create a "texture" for the text.The texture implies the systematic links that reinforce the text's solidarity and distinguish it from merely being a random collection of isolated sentences.

The Relationship between Coherence and Cohesion
Several researchers have found that different textbooks and composition books present confusing or even false definitions of coherence (Johnson, 1992).They defined coherence narrowly as cohesion.Nevertheless, this idea has been disapproved in several studies which claim that cohesion is the effect of coherence, not the cause and therefore they should be treated separately (Bamberg, 1983;Brostoff, 1981).Cohesive ties themselves are not enough to propel coherence in the text (Stotsky, 1983).
To understand why cohesion cannot cause coherence, let's examine the example below: "Jenny is a nurse, so she is young." In the example, even though the writer attempts to use different kinds of cohesive devices (reference 'she' and conjunction 'so'), the text still does not make sense.Hence, cohesion cannot cause coherence.
Halliday (1976) also noted that cohesion plays its main role in linking linguistic items and does not involve the semantic aspect of the text.Therefore, cohesion only has effects on the surface-level links of the text.
On the other hand, some other studies asserted that there is a correlation between coherence and cohesion and their impact on writing quality (Fitzgerald & Spiegel, 1986;McCulley, 1985).Both cohesion and coherence enhance the writing quality because using cohesive devices wisely and adequately can make the text clearer; as a result, it would be more coherent and easier for the reader to understand.

Review of Previous Studies
The notion of theme and rheme has become a topic of interest for many linguists and researchers; in recent decades, many studies have been conducted to discover theme-rheme problems and the impact of thematic progression on essays.
Theme-rheme problems were studied by Bloor & Bloor (1992), Arunsirot (2013), and Kuswoyo (2017).Arunsirot and Kuswoyo complemented several new theme-rheme problems to three main ones put forward by Bloor and Bloor (brand new theme, double rheme, and empty rheme).However, which theme-rheme problems appearing most frequently in academic writing have not been determined.Meanwhile, identifying common theme-rheme problems would be helpful to EFL teachers to diagnose and address students' mistakes.
In the current literature, many studies paid attention to analyzing the correlation between thematic progression and the marking of coherence and cohesion (Jingxia & Li, 2013;Soleymanzadeh & Gholami, 2014;Nguyen, 2021;Saeed, Karim, & Mughal, 2021).Another field of interest is instructions of thematic progression application in teaching writing which was conducted by Wang (2007), and Le & Wijitsonpon (2015).Although all of the above-mentioned studies came to a conclusion that thematic progression was a powerful tool for students to upgrade their coherence and cohesion and also for teachers to assess students' writing skills comprehensively.
Those studies barely measured to what extent the use of thematic progression improves coherence and cohesion in writing.This gap is worthwhile to research because understanding the extent to which thematic progression improves coherence and cohesion would be meaningful and compelling evidence to prove that learning this theory could outperform learning sentence-level skills in writing training.
Teaching theme-rheme and thematic progression are essential in writing training (Bloor & Bloor, 1992;Eggins, 2004;Wang, 2007;Vande Kopple, 1991).Jing (2015) and Nguyen (2021) incorporated the theory into an academic curriculum; they also devised lesson plans for teaching the theory.However, the problems or obstacles students undergoing when they were acquiring and applying the theory have yet to be explored.This gap needs to be filled so that other teachers can envisage their students' problems while perceiving the theory, then teachers can tailor lesson plans to suit students' capabilities.
Such gaps mentioned in the current body of research well justify the necessity of carrying out this study with three main research questions, including: (1) What theme-rheme problems do Vietnamese EFL students encounter while writing English academic essays?
(2) To what extent does the use of thematic progression theory in teaching help improve the coherence and cohesion in the students' essays?
(3) What problems do the students encounter in employing thematic progression theory in writing essays?
The research is significant in that it provides experimental data on the importance of thematic development in the teaching of coherence and cohesion.It will not only assist EFL teachers in teaching and assessing students' writing skills, but it will also help learners understand coherence and cohesion more thoroughly as well as practice producing well-knit essays.

Research Design
The design of this study is action research.Kemmis & McTaggart (1988) asserted that action research is a tool for teachers and educators to pursue effective pedagogical practices, improving the quality of teaching to enhance students' engagement and learning.Action research is directly concerned with promoting more effective L2 teaching and learning approaches (Mckay, 2006).Teachers can utilize action research to improve their teaching skills or to validate or assess the effectiveness/success of a particular teaching/learning technique when implemented in the real world.

Study Setting
The study was conducted on participants who were senior students at Hanoi National University of Education (HNUE).This university is one of the most prestigious universities in Vietnam.The study was carried out from October 17th to November 30th in 2021, lasting six weeks.Due to social distancing during the covid-19 pandemic, the whole process was executed online via the Zoom application.

Participants
In this study, the population consisted of 20 seniors majoring in English at Hanoi National University of Education.They are at the age of 21 and share the same culture since they are all Vietnamese.Their English competency ranges from 4.5 to 6.0 band scores in IELTS.
The reason for choosing this group of participants was that they shared the same writing style as most English learners in Vietnam.The participants in particular, and EFL learners in general, mainly focused on using sophisticated vocabulary and grammar structures without a fundamental understanding of English academic writing style.Therefore, the results from the population could be generalized, benefiting more English learners and teachers.

Action Plan Procedure
Kemmis and McTaggart's (1988) Action Research Model was adapted in this action research project.The study procedures were executed in one cycle lasting six weeks in the following phases: Plan, Action, Observe and Reflect.

Plan Phase
In the first week, the participating students were asked to do a pre-test and then read the materials before the course started.This activity was supposed to accelerate and facilitate students' learning ability, getting them ready to obtain the theory of thematic progression.Besides, the researcher inspected the students' pre-test essays to detect their writing problems, then preparing the lesson plans to deal with the problems properly.

Action and Observe Phase
All teaching sections followed the same pattern: Pre-class, In-class, and Post-class.
During the pre-class period, the researcher gave the learners handouts about the concept they were going to learn and some questions.By answering these questions, the learners would build a rudimentary foundation of thematic progression, and then they could understand the theory in more depth when learning with the teacher.
In the in-class period, the students were taught about thematic progression, as follows: • Practice employing thematic progression theory (particularly rheme-theme pattern) During the post-class period, the students were asked to write journals based on some guiding questions to reflect their learning process, the majority of the questions centered around exploiting students' challenges in absorbing and using the knowledge.

Reflect Stage
In the sixth week, in order to reflect on the students' improvement, the teacher required them to do post-tests.The data from post-tests was compared with that from pre-tests to determine the effectiveness of the theory.Also, the students' journals were analyzed to get insights into the barriers that hinder students' applying the theory in their writing essays.

Data Collection Instrument
The assessment of the students' writing skills was conducted by analyzing pre-test and post-test results.The tests were adapted from an IELTS writing task 2 retrieved from the website ieltsmaterial.com.The researcher also tried to select pre-test and post-test at the same intricate level with an expectation that there were no other unwanted elements that affected the results and the study's validity.The reason why choosing IELTS writing test as a mean in measuring of coherence and cohesion improvement is due to its reliable and well-rounded band rubrics.
Journals were used as a channel for the researcher to collect the students' feelings, attitudes, and difficulties during their learning process.Students were required to write their reflections on an e-board after each session.

Procedures of Essay Analysis
The analysis unit in this research is the "T-unit", which includes "an independent clause together with all hypotactically related clauses and words that are dependent on that independent clause" (Fries, 1995, p.49).T-unit analysis, according to many studies, is considered the most effective unit for analyzing themes in a text (Nguyen & Nguyen, 2018).The analysis process of pre-tests and post-tests went through the following steps: (1) Identifying T-units  The findings from pre-tests and post-tests show that the three most frequent problems that students create in their IELTS writing are "Inappropriate textual theme", "Empty rheme" and "Double rheme".

Thematic Progression Helps Improve the Coherence and Cohesion in Vietnamese EFL Students' Essays
Table 3 below shows the frequency statistics of coherence and cohesion scores in pre-tests.In the pre-tests, scores range from band 5 to band 7.In detail, the percentage of essays secured by band 5 is 35 percent (seven essays), the figure for band 6 is 40 percent (eight essays), and that of band 7 is 25 percent (five essays).The mean score of coherence and cohesion in pre-tests is roughly 5.9 (band 6).Table 4 below shows the frequency statistics of coherence and cohesion score in post-tests.Overall, in the post-tests, scores range from band 6 to 8; the range is not wider but the scores are higher than that of pre-tests.To be more specific, the percentage of essays obtained in band 6 is 25 percent (five essays), the figure for band 7 is 65 percent (13 essays), and that of band 8 is 10 percent (two essays).It is worth noting that in the post-tests, there are two essays that achieve band 8, while the highest band in pre-tests is just 7. The mean score of post-tests is 6.85.The findings show that after learning thematic progression, students had a visible improvement in coherence and cohesion from 5.9 to 6.85.Therefore, it could be finalized that by learning thematic progression theory, students could upgrade their coherence and cohesion to approximately one band.

Students' Difficulties in Using Thematic Progression Theory
The analysis of the students' journals helped detect some problems hindering students' learning abilities.

Difficulties in Theme Identification
In the students' first lesson journals, most of them found that identifying theme and rheme was not a challenging task.However, others who have a poor understanding of syntax struggle to locate themes in complex and compound-complex sentences.
4.3.2Inadequate Background Knowledge of the Topic Some students admitted that empty rheme is a significant problem for them.They are readily aware that the lack of idea elaborations creates empty rheme problems.However, due to their poor background knowledge, they struggle to elaborate points further.Therefore, in order to avoid empty rheme problems, students should do research and collect information about the writing topic firsthand.

Lack of Logical Thinking and Preparation
Some students reflected in their journals that because they do not make a logical and rational outline before starting to write, they tend to write based on their immediate thoughts.Therefore, their ideas usually are not well-organized and logical, putting irrelevant ideas in the same rheme of a sentence.

First Language Influences -Negative L1 Translation
Many students confessed that they directly translate what they are thinking in Vietnamese into written English when they are writing.This practice usually creates many issues in sentence linking, especially choosing inappropriate textual themes, because of the differences between Vietnamese thinking patterns and English.

Consuming Much Time to Apply Thematic Progression
The majority of students noted that using the thematic progression in writing was time-consuming because they had to review each sentence before writing it down; contemplating whether the theme/rheme is appropriate or not, and how to create reasonable thematic progression patterns.This cause their writing momentum to be interfered.

Discussion
The finding of coherence and cohesion improvement after learning thematic progression in this current research is in line with some previous studies (Jingxia & Li, 2013;Soleymanzadeh & Gholami, 2014;Nguyen, 2021;Saeed, Karim, & Mughal, 2021).These studies prove that the teaching of thematic is of some assistance to enhance coherence and cohesion in students' writings.It appears that the issues students face when using thematic progression could be the causes for common theme-rheme problems; for example, due to being neglect in organizing ideas, students might juxtapose two irrelevant rheme, which creates double rheme problem.Therefore, it could be said that students' writing difficulties and theme-rheme problems have a causal relationship.If EFL teachers and learners wish to solve writing problems at the root, it is necessary to take both aspects into consideration.
Despite the researcher's best efforts, some limits must be acknowledged.First of all, the population was rather small due to time constraints, which limited the results' generalization in terms of the efficacy of thematic progression.Second, because of the word count restrictions, some parts of the results may not be thoroughly investigated, leaving some of the points inadequately discussed.

Summary of the Findings
The findings in the study show that the most frequent problems students face in writing essays are inappropriate textual theme, empty rheme, and double rheme.It was also found that using thematic progression theory in IELTS writing could increase roughly one band in terms of coherence and cohesion.Lastly, the study found five difficulties and learning-related problems when studying and apply the theory: difficulty in theme identification, inadequate background knowledge, lack of logical thinking, first language influences, and time-consuming.

Implications
The findings from this study could be a reference resource for pedagogical and research purposes.Teachers can draw on the findings to incorporate the theory into their teaching context.Notably, teachers could also refer to the learning-related problems that students face when they perceive the theory; by doing so, teachers could customize the lesson plans, making them match their students' abilities.Furthermore, this research is expected to add to the field of Functional Grammar, and its findings may provide some useful background and a starting point for linguists and scholars interested in learning more about the subject.
theme could affect the tone and meaning of the utterances Second section • Five types of theme-rheme problems • Identifying theme-rheme problems in pre-tests • How to address theme-rheme problems Third section • Thematic progression patterns introduction • Types of theme-rheme repetition • Pattern comparison between Vietnamese texts and English texts Fourth section • How thematic progression could be applied in IELTS writing • Identify thematic progression patterns in Simon's essays (source: https://www.ielts-simon.com/)

( 2 )
Identifying theme and rheme in each T-unit (3) Identifying theme-rheme problems (4) Marking Coherence and Cohesion band based on IELTS band descriptor (5) Sending the marking paper to inter-rater to valid the score 4. Findings and Discussion 4.1 Theme-rheme Problems Created by Vietnamese EFL Students in Writing English Academic Essays 352 T-units in post-tests.The specific numbers and percentage of theme-rheme problems are shown in

Table 2 below . Table 2 .
Statistics of theme-rheme problems can be seen from the table that the percentages of inappropriate textual theme are highest in both pre-tests and post-tests with 7.25% (25 cases) and 2.8 % (10 cases), respectively.The proportions of empty rheme are second highest, with 3.77% (13 cases) in pre-tests and 2.0% (seven cases) in post-tests.The double rheme problems rank third with 1.45% (five cases) in pre-tests and 1.1% (four cases) in post-tests.The problems of brand new theme and overuse of constant theme patterns share comparable figures with about 0% of each.

Table 3 .
Frequency statistics of coherence and cohesion scores in the pre-tests

Table 4 .
Frequency statistics of coherence & cohesion scores in post-tests