INTRODUCTION
R ATIONALE OF THE STUDY
Vocabulary is fundamental to language, as highlighted by Hoshino (2010), and has gained significant attention in English language research (Bogaards & Laufer, 2004; Coady & Huckin, 1997; Erten & Tekin, 2008; Read, 2000; Richards & Renandya, 2002) Sarioglu (2018) emphasizes that language lacks meaning without vocabulary, making it a crucial focus in language teaching (Al Jabri, 2005) and a key factor in second language acquisition (Zargosh, Karbalaei, & Afraz, 2013) Willis (1990) famously noted that while grammar is important, vocabulary is essential for communication, stating, “without grammar very little can be conveyed, without vocabulary nothing can be conveyed” (p 111) Furthermore, Nation (2006) indicates that understanding a newspaper or novel requires a vocabulary of 8,000 to 9,000 words, achieving approximately 98% coverage.
Of the many dimensions of research in this area witnesses a variety of ways to study vocabulary where thematic clustering (Gholami & Khezrlou, 2013; Markman
& Hutchinson, 1984; Tinkham, 1997) is one approach beside the other type of word lists, namely taxonomic associate (Markman & Hutchinson, 1984), contextualization (Rahimi, 2014), semantic clustering (Finkbeiner & Nicol, 2003; Hashemi &
Gowdasiaei, 2005; Waring, 1997), code-switching and code-mixing (Ayemoni, 2006; Amuda, 1989; Atoye, 1994; Belly, 1976; Bokamba, 1989), to name a few
The distinctiveness hypothesis, supported by researchers like Tinkham (1997, 2000), suggests that thematic clustering is a lexical set of vocabulary organized around a specific schema formed by related groups of words Tinkham (1997) and Rahimi (2014) explain that thematic clustering enhances lexical retention by minimizing interference from competing concepts, such as semantic clustering (Ishii, 2013; 2014) This psychological association of closely related words not only aids in memory but also reinforces the importance of thematic concepts in language learning.
Research indicates that Vietnamese learners exhibit limited vocabulary knowledge, particularly in understanding equivalent meanings and word forms (Dang, 2020; Nguyen, 2017; Tran, 2013; Vu & Nguyen, 2019) Furthermore, thematic clustering has garnered significant empirical attention in contexts where English is either a first or second language, with previous studies primarily focusing on bilingual or monolingual participants (Sarioglu & Yildirim, 2018; Zarei & Adami, 2013; Zarei & Arasteh).
Despite the presence of empirical studies on thematic clustering, there remains a significant gap in its application within English learning environments for non-native speakers Previous research has often relegated thematic clustering to a secondary role, overshadowed by other lexical categories such as semantic clustering, contextualization, and code-mixing.
Thematic clustering, as noted in various studies, including Tinkham (1997), can exhibit varying degrees of impact that warrant further investigation Additionally, the level of participants involved in these studies raises important considerations regarding the outcomes.
Previous studies have primarily focused on specific groups of learners, such as advanced students or very young children, which raises the question of whether research on thematic clustering among different learner levels, like elementary or pre-intermediate, could yield different results Additionally, since existing empirical studies rely on immediate and delayed posttest outcomes, their findings are largely numerical and may not accurately represent the effectiveness of thematic clustering, leaving its true impact on learning unproven.
The current study emphasizes the importance of thematic clustering in research, positioning it alongside unrelated clustering to evaluate its effects on recognition and retention By specifically targeting pre-intermediate English language learners, this paper explores the influence of thematic clustering while also examining students' attitudes and behaviors towards this approach.
S TATEMENT OF PURPOSE
This study investigates the impact of thematic clustering on vocabulary acquisition through a single-subject experimental design The experiment's findings will assess how thematic clustering influences vocabulary learning Additionally, a post-interview will be conducted to examine the attitudes and behaviors of participants who engaged with thematic clustering.
R ESEARCH HYPOTHESES
The proposed hypotheses of the study are laid out as follow:
H1: Students believe that studying vocabulary using thematic clustering facilitate the process of vocabulary acquisition of students rather than using unrelated clustering
H2: Studying vocabulary using thematic clustering can enhance students’ vocabulary recognition and production
Also, the null hypotheses are hereby set out:
NH1: Students believe that studying vocabulary using thematic clustering hinder the process of vocabulary acquisition of students rather than using unrelated clustering
NH2: Studying vocabulary using thematic clustering cannot enhance students’ vocabulary recognition and production.
S IGNIFICANCE OF THE STUDY
This study serves multiple purposes, benefiting students seeking effective vocabulary learning methods and those interested in exploring various approaches to acquiring new words Additionally, course designers, textbook authors, and educators can leverage the findings to adapt or create course materials using thematic or unrelated strategies, or a blend of both Lastly, the research contributes to future studies on thematic clustering in Vietnam or in the broader context of English as a foreign language.
O VERVIEW OF THE THESIS CHAPTERS
This study is structured into five chapters, beginning with an introduction to thematic clustering and its significance in vocabulary learning The second chapter explores theoretical perspectives and summarizes empirical evidence related to thematic clustering The methodology is examined in the third chapter, providing insights into the research topic and phenomenon Chapter four presents the study's findings, confirming earlier hypotheses and discussing comparisons with previous research Finally, chapter five concludes the paper with a summary, outlines limitations, and offers recommendations for future research.
LITERATURE REVIEW
R ELEVANT THEORIES
The study builds on Tinkham's (1997) ultimate theory, which posits that words from various semantic or thematic clusters can be categorized under a unifying concept known as frames, as per schemata theory Tinkham explains that lexical items sharing similar features can be grouped together, enhancing their distinctiveness in memory Additionally, Hunt and Elliot (1980) highlight that long-term memory is influenced by items that share semantic and thematic connections Consequently, the distinctiveness hypothesis suggests that manipulating the distinctiveness of lexical items can improve memory retention, a concept that will be explored in detail in this section.
Numerous empirical studies have focused on the impact of semantic clustering (Tinkham, 1997; Waring, 1997) Tinkham's 1997 research introduced a novel approach known as thematic clustering, which has since gained popularity, leading to the terms thematically associated clusters and thematically related clusters being widely used in the literature (Allahverdizadeh, Shomoossi, Salahshoor).
Thematic clustering, as defined by Tinkham (1997), involves the combination of words from various parts of speech that are interconnected by a common thematic concept, reflecting psychological associations This organization arranges words from different syntactic categories that relate to the same circumstances, forming a cohesive unit that co-describes a specific situation, grounded in the theory of semantic frames (Allahverdizadeh et al., 2014; Chepyshko & Truscott, 2009) Tinkham (1997), referenced in Hippner-Page (2000), asserts that thematic clustering engages both cognitive and linguistic processes, fostering an enhanced word learning environment The relationship between thematic clustering and its practical applications is explored in subsequent sections.
The recognition of thematic clusters can be understood through the concept of a "semantic frame," which reflects individuals' knowledge of specific lexical patterns and the contextual backgrounds associated with the words (Zarei & Arasteh, 2011) Allahverdizadeh et al (2014) further elaborated that while lexical items belong to distinct syntactic and semantic categories, their relevance is tied to certain frames or concepts that represent a speaker's underlying knowledge, known as "schemata." The theory of schemata will be explored in more detail in a subsequent section.
The earliest definition for schemata theory came from the study of Bartlett
Schemata theory, as articulated by Fillmore (1985), explains how human knowledge is organized and stored in the brain, focusing on methods of knowledge acquisition and application (Tracey & Morrow, 2006) This theory encompasses three key aspects identified by Reason (1990): unconscious mental structures, the framework of prior knowledge, and the active imagery that constitutes long-term memory Alshaikhi (2011) illustrates this concept with the term "deposit," demonstrating that when an individual thinks of a "bank," related terms such as "cheque," "customer service," and "money" are activated, showcasing the interconnectedness of lexical items in our cognitive processes.
While the concept of “semantic clusters” can be denoted by the area of
The concept of "semantic fields" was expanded by Fillmore (1985) through the introduction of "thematic clusters" or "semantic frames," which are part of the broader theory of schemata (Tinkham, 1997) Subsequent research, including studies by Goetz, Anderson, and Scharlett (1981) and Smith, Adams, and Schorr (1978), has supported this theory Goetz et al found that sentences with higher integration and schema-related information are easier to learn compared to those with unrelated lexical items Similarly, Smith et al reached a parallel conclusion, emphasizing the importance of whole sentence adjustments over individual phrases or clauses.
The study highlights that the facilitating effect observed is attributed to the absence of familiarity with unrelated semantic information This finding supports the application of schemata theory within educational settings, demonstrating its relevance in enhancing comprehension and learning processes.
& Schorr, 1978) The contribution function of schemata theory to the distinctiveness hypothesis will be discussed in later section
Thematic clustering can be better understood through distinctiveness hypotheses, which suggest that memory stores words as smaller features, encompassing both nonsemantic elements like orthographic and phonemic representations, as well as semantic features that relate to conceptual meaning According to Hunt and Elliot, these features differ not only in nature but also in their effectiveness for memory restoration, particularly regarding trace durability Nonsemantic information tends to be transient and does not aid long-term memory, whereas semantic information plays a crucial role in enhancing memory retention.
Previous research has explored the effectiveness of semantic information through various encoding conceptualizations, including stage levels and levels of processing Studies supporting the stage levels approach indicate that short-term memory retains transient, nonsemantic information, while long-term memory holds more durable, semantic information Conversely, the levels of processing approach emphasizes that the qualitative features of words influence retention, with semantic processing yielding better performance and stronger trace durability compared to nonsemantic processing Overall, the findings across these studies affirm the significant impact of semantic information on long-term memory and retention, although the stage levels data often lack clarity regarding the direct role of semantic information, instead suggesting a negation of nonsemantic influences.
The distinctiveness hypothesis, a key modification of the levels of processing approach, emphasizes the role of distinctive features in memory retention, as highlighted by Eysenck (1979) and others According to Hunt and Elliot (1980), distinctive features can be semantic or nonsemantic and are defined as the common lexical representation shared by words Their experiments demonstrated that enhancing distinctive features improves recall, linking retention to the degree of lexical representation among words The study concludes that distinctive features can vary widely and that manipulating items with shared distinctive features can enhance recognition and recall Subsequent research has further applied the distinctiveness hypotheses, establishing it as a framework for evaluating the retention quality of word features and their trace durability, focusing on how well these features are retained over time.
The distinctiveness hypothesis, which posits that increased nonsimilarity among lexical items enhances learning ease, has been explored in various studies (Hippner Page, 2000; Mirijalili et al., 2012; Tinkham, 1997) This framework underpins the current study, emphasizing the importance of semantic and thematic vocabulary in the learning process.
P REVIOUS STUDIES
Numerous studies have explored the impact of thematic clustering on vocabulary acquisition, highlighting its significance in language learning (Al Shaikhi, 2011; Allahverdizadeh et al., 2014; Hippner-Page, 2000; Hoshino, 2010; Zargosh et al., 2013; Khayef & Khoshnevis, 2012; Mirjalili et al., 2012; Rahmati & Helmiyadi, 2021; Tinkham, 1997; Zarei).
Research on thematic word lists reveals a divided opinion among scholars Some studies indicate that these lists enhance vocabulary acquisition, supporting receptive and productive language skills (Allahverdizadeh et al., 2014; Rahmati & Helmiyadi, 2021; Hippner-Page, 2000) Conversely, other researchers argue that such organizational methods may have no significant impact or could even impede learners' ability to remember and utilize new vocabulary (Al Shaikhi, 2011; Hoshino, 2010).
According to Rahmati & Helmiyadi (2021), a critical need for learners is to grasp new concepts, which is significantly aided by a strong understanding of vocabulary Mukoroli (2011) further supports this by highlighting that a decline in text comprehension leads to increased difficulty with word meanings.
Vocabulary acquisition is influenced by the methods employed in learning new words, as highlighted by Rahmati and Helmiyadi (2021) Research has explored thematic clustering in comparison to various types of word lists, demonstrating its significance in vocabulary learning (Hippner-Page, 2000; Zarei & Arasteh, 2011; Zargosh, Karbalaei & Afraz, 2013).
Zarei and Arasteh (2011) conducted a study that combined thematic grouping with code-mixing and contextualization, utilizing proficiency tests to evaluate the effectiveness of each method on L2 vocabulary recognition and production Their findings revealed that thematic clustering yielded the most significant results, while code-mixing and contextualization did not demonstrate notable differences among the various groupings.
Zargosh, Karbalaei, and Afraz (2013) explored the impact of thematic clustering on vocabulary acquisition among both monolingual (L1) and bilingual (L2) learners Their study revealed that while thematic clustering benefits vocabulary learning for both groups, it has a more pronounced effect on L2 students, enhancing their ability to acquire new words effectively.
Research by Zarei and Adami (2013), similar to the findings of Zargosh, Karbalaei, and Afraz (2013), indicates that thematic clustering and notebook keeping significantly enhance L2 learners' vocabulary recognition and retention compared to semantic mapping While all three methods prove effective for vocabulary production, thematic clustering emerges as the superior technique for both receptive and productive vocabulary knowledge, aligning with Khayef and Khoshnevis’s (2012) perspective discussed later in this chapter.
Tinkham (1997) introduced a clustering method that categorizes clusters into related-unrelated semantic and associated-unassociated thematic groupings In a mixed factorial design study, Tinkham explored whether participants found it more challenging to learn related or unrelated semantic clusters, as well as associated or unassociated thematic clusters The study utilized sets of artificial words, adhering to strict rules and conditions to control the learning environment.
In a 1997 study, it was found that the number of trials required for vocabulary acquisition varies among subjects The research revealed that semantic clustering hinders the learning process, while thematic clustering enhances it, making it easier for learners to acquire new words Additionally, students demonstrated a greater ease in learning thematically related word sets compared to those that were unassociated.
In a study by Allahverdizadeh, Shomoossi, Salahshoor, and Seifoori (2014), which builds on Tinkham's (1997) research, the impact of thematic and semantic word lists on elementary learners with bilingual backgrounds was explored The findings reinforced Tinkham's conclusion, indicating that thematically associated sets had the most significant effect on learning, followed by semantically unrelated and thematically unassociated clustering, while semantically related clustering proved to be the least effective method.
Khayef and Khoshnevis (2012) conducted a study examining the effects of semantic and thematic clustering on immediate vocabulary recall and retention among EFL learners Their experimental design revealed that thematic clustering significantly outperformed semantic clustering in immediate posttests and retention assessments While semantic clustering showed better results than a comparison group in immediate recall, it did not demonstrate the same effectiveness in delayed retention tests Consequently, the researchers concluded that thematic grouping has a more substantial impact on vocabulary retention compared to semantic clustering.
A study by Rahmati and Helmiyadi (2021) explored the impact of thematic vocabulary cards on enhancing primary school students' English vocabulary through classroom action research The findings highlighted the importance of thematic clustering in improving students' ability to recognize and retain new vocabulary presented in descriptive texts.
Previous research often focused on thematic clustering in isolation, assessing word receptiveness and retention without considering context (Tinkham, 1997) In contrast, Mirjalili, Jabbari, and Rezai (2012) explored the impact of semantic and thematic clustering in both isolated and contextualized settings across three learner levels: elementary, pre-intermediate, and intermediate Their findings indicated that thematic clustering significantly improved word recall in contextualized settings, while learners tended to perform better when learning unrelated word sets in isolation.
Contrasting views suggest that thematic clustering may not significantly aid vocabulary learning, as evidenced by studies from Al Shaikhi (2011), Hoshino (2010), and Smiley and Brown (1979) Smiley and Brown (1979) explored how age influences preferences for thematic versus taxonomic matching tasks, finding that while young and older individuals favor thematic organization, middle school students and adults lean towards taxonomic systems They noted that these shifts reflect preference changes rather than a new method of knowledge organization Conversely, Hoshino (2010) found thematic clustering to be less effective compared to other categorization types, concluding that categorical lists outperform thematic ones, which contradicts Tinkham's (1997) findings.
Inspired by Tinkham (1997), Al Shaikhi (2011) examined the most effective vocabulary clustering methods for advanced Arabic-speaking learners, focusing on retention and acquisition By utilizing Tinkham's framework and incorporating the work of Allahverdizadeh et al (2014), the study categorized vocabulary into semantically related, semantically unrelated, and thematically related clusters Although immediate test results showed no significant differences among the three groups, semantically related and unrelated clusters demonstrated better performance than thematic clusters in delayed tests Consequently, thematic clustering was deemed the least effective method for vocabulary retention and acquisition.
METHODOLOGY
R ESEARCH DESIGN
This study adopts a single-subject design to investigate the effects of thematic clustering on vocabulary recognition and retention, diverging from traditional experimental approaches By focusing on individual cases, the research aims to elucidate the causal relationship between the intervention and its outcomes, as supported by Nock et al (2007) Creswell (2012) highlights that this design involves observing subjects over a baseline period before implementing an intervention, allowing for a detailed analysis of learning processes The study anticipates that by examining students' learning of unrelated clustered vocabulary prior to the thematic clustering intervention, it can assess the intervention's impact on vocabulary retention and recognition A distinctive feature of the single-subject design is that each participant serves as their own control, enhancing the validity of the findings (Cooper et al., 1987; Neuman).
& McCormick, 1995), which was also facilitate the purpose of this research, i.e to observe the behaviour and attitude of each student given treatment
This study defined independent variables as the type of clustering—either unrelated or thematic—while the dependent variable was based on students' results By leveraging both qualitative and quantitative data, the research aimed to provide a comprehensive analysis of the problem (Creswell & Creswell, 2018) The study combined quantitative test scores with qualitative interview recordings to evaluate the distinctiveness hypothesis and the attitudes and behaviors of participants.
The research consisted of three key phases: a non-treatment baseline, an intervention with treatment, and follow-up interviews Initially, a pre-interview filtered out students with prior knowledge, forming part of the non-treatment phase During this baseline period, the researcher established a stable understanding of students' vocabulary learning methods, minimizing the likelihood of any behavioral trends prior to the intervention (Poling & Grosset, 1986; as cited in Creswell, 2012) The intervention phase involved frequent observations and scoring, revealing changes in student behavior as they engaged with the thematic clustering approach (Creswell, 2012) The focus was on individual data plotting rather than group results, leading to a final post-treatment interview phase where quantitative data from earlier tests was analyzed alongside students' reasoning.
R ESEARCH INSTRUMENTS
This study utilized a single-subject design featuring a basic reversal pattern, which included a baseline phase followed by an intervention treatment During the baseline, students were exposed to unrelated sets of lexical items, while the intervention phase introduced thematic clustering of vocabulary to assess its impact Performance metrics were gathered through a series of immediate and delayed tests, aligning with methodologies used in previous research by Hoshino (2010) and Khayef and Khoshnevis.
(2012), Markman (1984), Mirjalili, Jabbari and Rezai (2012) and the one of Rahimi
In 2014, a study was conducted to evaluate the effectiveness of the distinctiveness hypothesis, incorporating pre- and post-interviews to capture participants' attitudes and behaviors towards unrelated and thematic categorization This research aimed to fill a gap in previous evidence by providing interview data that was previously lacking (Allahverdizadeh et al., 2014; Alshaikhi, 2011; Hippner Page, 2000; Hoshino, 2010) Observations were carried out following a procedure similar to that of Tinkham (1997) throughout the study.
In this study, firstly, the vocabulary used in the study and the posttest in both baseline and intervention sections were adapted from the book "English Vocabulary
In Use: Advanced Level" (McCarthy & O'Dell, 2017) Regarding the pre- and post- intervention interview, the interview questions were created by the researcher
The study utilized 120 vocabulary items from "English Vocabulary In Use: Advanced Level" (McCarthy & O'Dell, 2017), selected equally from 12 units that correspond to the B2 to C1 levels on the CEFR scale This choice aimed to ensure uniformity in difficulty, as the participants were at a pre-intermediate level By selecting advanced vocabulary, the researcher aimed to minimize prior familiarity with the items, thereby reducing the influence of extraneous variables Additionally, the thematic presentation of the lexical items aligned with the study's objectives, making this course book a preferred option over others.
The vocabulary items were selected from 12 distinct themes, with the first 6 arranged randomly into 6 sets of unrelated clustering vocabulary, each containing 10 items The remaining 6 themes maintained their thematic order All vocabulary was utilized during the learning phase, with Vietnamese definitions provided for each item to enhance comprehension This approach prioritized presenting the most relevant meanings to facilitate effective testing By leveraging L1 equivalence, learners could form stronger associations between English words and their Vietnamese meanings, thereby improving learning efficiency through pair-association techniques (Morikawa, 1955; Tagashira, 2010).
A total of 12 immediate posttests were developed using materials and exercises from the same textbook (see Appendix C) These posttests were split into two parts: the first half for the non-treatment period and the latter for the intervention phase To maintain variability, the order of items in the tests was randomly reversed compared to the learning phase Additionally, the first six posttests featured shuffled items to ensure unrelated clustering in the questions.
Six posttests were structured similarly to the thematic clustering items, featuring a randomized order of questions Each posttest included 10 gap-filling questions, ensuring consistency across different arrangements.
The delayed post-tests comprised 120 questions, utilizing materials from the same course book alongside definitions from the Oxford Advanced Learner's Dictionary These tests were structured into two parts: one focusing on unrelated items and the other on thematic vocabulary Each test featured six sections with 60 vocabulary items presented in sets of 10, formatted as gap-filling exercises This organization aimed to reduce student confusion when tackling a test with a substantial number of questions.
This study utilized two sets of interviews to investigate students' vocabulary learning methods and their attitudes before and after experiencing thematic clustering The aim was to assess the impact of thematic clustering and validate the distinctiveness hypothesis through interview results and test data Conducted in Vietnamese to accommodate learners' potential difficulties in articulating responses, the data were subsequently translated into English by the researcher.
The researcher developed three open-ended interview questions to allow participants the freedom to express their thoughts (see Appendix D) The first question focused on investigating students' current vocabulary learning methods, which also helped identify those with prior knowledge The remaining two questions aimed to understand students' perceptions of vocabulary learning using both unrelated and thematic word lists Prior to gathering opinions, the researcher provided a clear explanation of these two types of clustering, accompanied by illustrative examples.
The researcher developed five open-ended interview questions to encourage detailed responses from students (see Appendix E) The first two questions aimed to explore participants' feelings and attitudes towards their experiences in both phases, allowing for a comparison of their reactions to the baseline and intervention methods The third question assessed students' perceptions and preferences regarding each method used The fourth question required students to evaluate and compare the effectiveness of the different clustering techniques they experienced Finally, the last question sought participants' suggestions for pedagogical implications, specifically the types of clustering they would recommend for classroom implementation.
Throughout the study, observations were made during pre- and post-interviews, where the researcher moderated to clarify participants' responses During the intervention, the researcher took essential steps to ensure that students did not record or note down vocabulary in any form, maintaining the integrity of the experiment's objectives.
The researcher monitored the time spent presenting vocabulary, ensuring to stop screen sharing after four minutes, and also recorded the duration students took to complete their tests.
P ARTICIPANTS
The study involved six university students aged 18 to 22 from various universities in Ho Chi Minh City, all enrolled in three different classes at an English center These participants were selected based on their pre-intermediate English proficiency level, as previous research predominantly focused on either advanced learners (Tinkham, 1997; Hippner Page, 2000; Markman, 1984) or beginner learners, specifically children aged 3 to 5 (Smiley & Brown).
In 1979, research focused on participants at the elementary or pre-intermediate English level received minimal attention The study utilized purposeful sampling to select participants who shared the same English proficiency, ensuring they were from different classes but at the same level Volunteers were chosen to engage in the experiment, which included three phases: the baseline, intervention, and interview All six participants individually participated in each component of the experiment.
R ESEARCH PROCEDURE
The study was conducted over a 7-week period, consisting of 4 weeks of treatment (either intervention or non-intervention), followed by 2 weeks for delayed testing and a final week for post-treatment interviews Delayed tests were administered one week after each treatment phase, supported by empirical research (Hippner Page; Hashemi & Gowdasiaei, 2005) All treatments and interviews were conducted individually and virtually via Google Meet The research procedure was divided into three phases, with the first phase spanning weeks 1 to 3, during which the initial two weeks included 6 sessions of non-treatment and immediate posttests, culminating in the first delayed posttest in week 3.
3 The intervention phase happened from week 4 to 6, with weeks 4 and 5 dedicated to treatments and posttests, and the second delayed posttest carried out in week 6 Finally, in week 7, the post-treatment interviews were conducted
Participants were informed one week prior to the intervention and a fixed schedule was established for their involvement As their teacher, the researcher assured them that their academic performance would remain unaffected by the study, and that participation would not provide any advantages over their peers.
Additionally, the students received a brief explanation about the project and the way it was carried out
3.4.1 Non-treatment and Treatment Period
Over a four-week intervention course, participants attended 12 study sessions, which included immediate post-tests conducted by the researcher The initial six sessions served as a non-intervention period, where students engaged with unrelated items and underwent corresponding post-tests In contrast, the final six sessions comprised the treatment period, featuring thematically categorized items and post-tests designed to evaluate their effectiveness.
During the study, each student participated in three sessions per week, each lasting about 20 minutes, where they learned 10 vocabulary items categorized either thematically or randomly through PowerPoint presentations provided by the researcher Students had a strict four-minute timeframe to study the vocabulary, as established by Mirjalili, Jabbari, and Rezai (2012), and were prohibited from taking notes to ensure objective results Following the study period, an immediate post-test was administered via a Google Form link, with no time limit; however, the researcher monitored the duration from when the test was sent until submission to maintain oversight.
The delayed post-tests were conducted one week after the completion of each part, specifically following sections 06 and 12 Although no specific time was allocated for these tests, the researcher made sure to document the duration.
The interviews were conducted in Vietnamese, with researchers serving as moderators to facilitate discussions by explaining concepts, asking follow-up questions, and clarifying the information gathered.
Before the non-treatment period, a pre-interview was conducted as part of the baseline phase Each participant was approached individually and without prior notice, with the entire interview lasting approximately 15 minutes Open-ended questions were utilized, and the responses were recorded for data collection.
Post-treatment interviews were conducted one week after the second phase of treatment, with each participant interviewed individually for about 30 minutes At the start of the interview, students were reassured that there were no right or wrong answers The interviewer utilized open-ended questions to foster communication and employed clarification questions to enhance data quality Efforts were made to encourage detailed responses, including explanations or examples, and all student answers were recorded with prior consent.
M ETHOD OF DATA ANALYSIS
A one-way analysis of variance (ANOVA) was conducted using SPSS version 22 to analyze the results of both immediate and delayed tests The interview data was transcribed and examined following Zoltan's (2006) four-step data analysis process Initially, the recordings were transcribed, followed by the preparation for pre-coding and coding After completing these phases, data from various displays were compiled to create a comprehensive data bank Ultimately, the data was interpreted, leading to the formulation of the final report.
FINDINGS AND DISCUSSIONS
F INDING
Before conducting the data analysis, Cronbach’s alpha was utilized to assess the reliability of the instruments, ensuring they met the internal consistency requirement The reliability coefficient was determined to be 0.847 for 24 items, indicating an acceptable level of internal consistency (α > 0.8) as per Peterson (1994).
Participants were assessed on two clustering methods: unrelated clustering and thematic clustering The results indicate that students performed better in thematic clustering (M = 5.42) compared to unrelated clustering (M = 4.08) The minimum and maximum scores for thematic clustering ranged from 3 to 8, surpassing those of unrelated clustering Both groups exhibited similar standard deviations (SD = 1.519 for thematic clustering and SD = 1.763 for unrelated clustering), suggesting comparable variability Additionally, the data showed no significant skewness, indicating a normal distribution for both clustering types (0.318 and 0.014, respectively), as illustrated in Figure 4.1.
Descriptive Statistics of Immediate Tests
A One-Way Repeated ANOVA was conducted to assess the statistical significance of vocabulary recognition differences between unrelated recognition and thematic clustering in immediate tests, given that the data followed a normal distribution.
9 clustering and thematic clustering The study considered the following null hypothesis and alternative hypothesis:
Null Hypothesis: There was no statistically significant difference between unrelated clustering and thematic clustering regarding vocabulary recognition
Alternative Hypothesis: There was a statistically significant difference between unrelated clustering and thematic clustering regarding vocabulary recognition
Due to the violation of Mauchly’s Test of Sphericity, the degrees of freedom were adjusted using the Greenhouse-Geisser correction, yielding a significant result (F(1, 35) = 15.56, p = 000) indicating a statistically significant difference between the two groups The Wilks’ Lambda statistic of 692 (p < 0.05) further confirmed a change in scores between the groups Additionally, a Partial Eta Squared of 308 indicated a very large effect size, as per Cohen's guidelines (1988) Consequently, the null hypothesis was rejected in favor of the alternative hypothesis, which posited that the two methods differ significantly.
Partial Eta Squared Immediate Pillai’s Trace 308 15.556 1.000 35.000 000 308
Tests of Within-Subjects Effects
Type III Sum of Squares df
Geisser 32.000 1.000 32.000 15.556 000 308 Huynh-Feldt 32.000 1.000 32.000 15.556 000 308 Lower-bound 32.000 1.000 32.000 15.556 000 308 Error
Greenhouse- Geisser 72.000 35.000 2.057 Huynh-Feldt 72.000 35.000 2.057 Lower-bound 72.000 35.000 2.057
The delayed test results indicated that students scored significantly higher on thematic clustering (M = 6.08, SD = 1.948) compared to unrelated clustering (M = 4.64, SD = 1.355), with maximum scores of 10 and 8, respectively Additionally, the data for both clustering types met the criteria for normal distribution, showing values of 0.311 for unrelated clustering and 0.540 for thematic clustering.
Descriptive Statistics of Delayed Tests
A One-Way Repeated Measures ANOVA was performed to analyze the production effect based on scores from two clustering types The study established both a null hypothesis and an alternative hypothesis for comparison.
Null Hypothesis: There is no statistically significant difference between unrelated clustering and thematic clustering regarding vocabulary production
Alternative Hypothesis: There is a statistically significant difference between unrelated clustering and thematic clustering regarding vocabulary production
The analysis revealed a significant difference between unrelated clustering and thematic clustering, with F(1, 35) = 14.53 and p = 0.001, indicating a violation of sphericity that was addressed using Greenhouse-Geisser degrees of freedom correction The findings showed a substantial effect size, with a Partial Eta Squared of 293, leading to the rejection of the null hypothesis in favor of the alternative hypothesis, as the results were statistically significant with p < 0.05.
Partial Eta Squared Delayed Pillai’s Trace 293 14.533 1.000 35.000 001 293
Tests of Within-Subjects Effects
Type III Sum of Squares df
Partial Eta Squared Delayed Sphericity Assumed 37.556
1 37.556 14.533 001 293 Greenhouse-Geisser 37.556 1.000 37.556 14.533 001 293 Huynh-Feldt 37.556 1.000 37.556 14.533 001 293 Lower-bound 37.556 1.000 37.556 14.533 001 293 Error
Greenhouse-Geisser 90.444 35.000 2.584 Huynh-Feldt 90.444 35.000 2.584 Lower-bound 90.444 35.000 2.584
4.1.2.1.1 Students’ normal way of vocabulary learning
Students typically adopt two primary methods for vocabulary acquisition: intentional and unintentional learning Those who learn unintentionally often acquire new words randomly, influenced by frequently used vocabulary, personal interests, or content encountered on social media For instance, one student emphasized that focusing on topics of interest makes learning more manageable, stating, "if we learn vocabulary based on topic, it will be too much to learn it all, so I just learn the one I like."
Learners who focus on intentional learning often rely on reading comprehension contexts, limiting their vocabulary acquisition to words within those contexts (A1, A2, A5) The sequence in which they learn vocabulary typically mirrors the order in which it appears in the text, whether by listing all items from a single paragraph or arranging them from top to bottom (A1, A2) One student shared her strategy of organizing words based on specific criteria, such as word forms or topics, stating, “I learn the words through reading passages; for example, after reading, I will list out the words based on the topic to learn” (A5).
Some students reported using multiple learning methods For instance, Student A3 mentioned, “I only learn vocabulary from the reading passages or specific topics while studying at school.”
4.1.2.1.2 Students’ perception about unrelated clustering
A study on vocabulary learning through unrelated clustering revealed that 4 out of 6 participants found this method challenging and difficult to retain The participants cited reasons such as the lack of relevance between vocabulary meanings and the inefficiency of memorizing disconnected lists Only one student reported a neutral experience with this approach, but she acknowledged that she would struggle to recall the words long-term, as she could only remember the sequence of letters without forming mental images of the vocabulary.
Learning new words is a common experience, and while I can grasp their meanings, retaining them for an extended period proves challenging This difficulty arises from my inability to visualize the items, leading me to focus on memorizing the arrangement of letters rather than their conceptual significance.
Only one student expressed a very positive preference for learning through unrelated clustering, stating that it helps her "maximize the words learned, the topic, as well as knowledge" (A4) She emphasized that her ability to learn words is driven by her interest and that her learning method is independent of the clustering types used.
Regardless of how vocabulary is organized, I believe I can still retain it For me, remembering words hinges on my desire to learn them, meaning that factors like lexical arrangement do not impact my ability to recall them.
4.1.2.1.3 Students’ perception about thematic clustering
Participants unanimously agreed that thematic clustering significantly enhances vocabulary learning and retention They noted that this method creates a cohesive theme or context that connects related items, aiding in memorization Student A6 echoed this sentiment, explaining that she could visualize an "imaginary picture" by linking the images of each word However, she expressed a concern that while thematic clustering aids in short-term retention, it may not be as effective for long-term memory Nevertheless, she acknowledged its value in expanding her vocabulary.
(a common theme or topic) instead of horizontally (a different theme or topic).”
4.1.2.2.1 Students’ perception about unrelated clustering
D ISCUSSION
4.2.1 Studying vocabulary using thematic clustering facilitate students’ vocabulary acquisition
The study indicates that thematic clustering significantly enhances vocabulary acquisition among students, particularly at the elementary level, aligning with Allaverdizadeh et al (2014), who found that participants recall more words from thematic sets compared to other categorization methods The researcher notes that the effectiveness of this approach diminishes as students' proficiency levels increase, suggesting a mismatch between proficiency and the benefits of thematic features This observation is supported by Al-Jabri (2005), who states that higher proficiency reduces the necessity for word categorization Thus, the findings imply that lower-level students experience a stronger impact from thematic clustering, providing insight into the study's results.
The distinctiveness hypothesis and schema theory are supported by the current findings, aligning with Mirjalili, Jabbari, and Rezai's (2012) research that emphasizes the benefits of thematic clustering in enhancing students' learning, especially when integrated with contextual-based learning Additionally, Hoshino (2010) provides insight into this phenomenon, suggesting that when two words share smaller features, as seen in thematic clustering, they offer supplementary functions that aid memory retention, in contrast to synonyms that share larger overlapping features.
The position of the English language in the learning environment is crucial, as evidenced by the findings of Zargosh, Karbalaei, and Afraz (2013) Their research indicates that the benefits of thematic clustering on vocabulary acquisition extend beyond monolinguals and bilinguals, impacting learners in contexts where English is a foreign language This suggests that thematic clustering serves as an independent factor in enhancing vocabulary, irrespective of the surrounding linguistic environment.
The current study contradicts the findings of Hippner-Page (2000) and Smiley and Brown (1979), which suggest that thematic clustering has a neutral effect on students compared to other techniques Hippner-Page (2000) posits that the effectiveness of clustering may increase with students' familiarity, while Smiley and Brown (1979) argue that any equal influence observed might stem from changes in preference rather than concrete assumptions Additionally, the results of this study differ from those reported by Zarei and Adami.
A 2013 study suggests that thematic clustering does not affect vocabulary presentation, aligning with the interference hypothesis, which continues to be a debated alternative to the distinctiveness hypothesis.
4.2.2 Studying vocabulary using thematic clustering facilitate students’ vocabulary recognition and production
The study demonstrates that thematic clustering significantly enhances vocabulary recognition and production among students compared to unrelated clustering This finding aligns with Tinkham’s (1997) assertion that thematic clustering facilitates learning through improved vocabulary recall, supporting both the distinctiveness hypothesis and schema theory However, this perspective contrasts with the views of Al Shaikhi (2011) and Sarioglu.
Yildirim (2018) challenges the idea that thematic clustering positively impacts vocabulary acquisition, arguing instead that educators should focus on the quantity of words taught and the instructional methods employed, rather than the approach to clustering (Sarioglu & Yildirim, 2018).
The enhancement of vocabulary recognition and retention does not always exhibit a symmetrical correlation Research by Khayef and Khoshnevis (2012) supports this, highlighting that thematic clustering plays a more significant role in word recall than in word production Consequently, it is essential to consider these two aspects as distinct approaches, as demonstrated in the studies by Rahimi (2014) and Zarei and Arasteh.
The findings from 2011 align with the current study regarding vocabulary retention, indicating that thematic clustering aids in vocabulary production However, they contradict the current study's results on vocabulary recognition, as thematic clustering does not appear to enhance this aspect Consequently, Khayef and Khoshnevis (2012) recommend that teachers should dedicate time to train students on effectively utilizing thematic clustering for optimal benefits.
CONCLUSION
T HE HYPOTHESES REVISITED
Research indicates that thematic clustering enhances vocabulary recognition and retention Furthermore, it supports the idea that this method aids vocabulary acquisition for non-English speaking learners, as evidenced by students' preferences and positive attitudes towards thematic clustering.
I MPLICATIONS
This paper offers significant insights that enhance the understanding of educational theories and principles The study's findings can inform and shape pedagogical practices, providing a broader perspective on their implications Ultimately, the implementations outlined in this paper serve as a valuable resource for educators, researchers, and textbook designers looking to integrate these insights into their work.
The distinctiveness hypothesis is a prominent model in clustering research, utilized across various fields such as classification, document retrieval, and image segmentation It posits that items within a cluster exhibit greater similarity to one another than to those outside the cluster This paper argues that the distinctiveness hypothesis remains valid when examining the effectiveness of thematic clustering, as participants tend to recall more distinctive items compared to non-distinctive ones.
5.2.2 Implications for teaching English vocabulary and developing materials
This study offers valuable insights for material developers and textbook designers focused on lexical categorization and vocabulary enhancement It suggests that vocabulary items should be organized thematically rather than alphabetically or by proficiency level The research advocates for teachers to adopt this clustering approach in their English vocabulary instruction, especially to boost students' word retention and comprehension However, it is essential to carefully evaluate the effectiveness of thematic clustering compared to other word categorization methods before fully embracing it as a superior strategy.
This study highlights the importance of research methodology, recommending the use of experimental research, specifically single-subject studies, to engage students—who are central to the learning process This approach allows for a deeper understanding of both statistical data and the personal experiences and voices of the students involved.
L IMITATIONS OF THE STUDY AND RECOMMENDATIONS FOR FUTURE RESEARCH
While the study employs triangulation to support its statistical and theoretical generalization, its limitations include a small sample size due to the single-subject nature of the research The study focuses on a narrow range of pre-intermediate proficiency levels and specifically examines only two types of clustering, which restricts its scope compared to the broader context of word categorization Consequently, the findings may not be applicable to larger sample sizes with varying proficiency levels or when considering additional types of clustering.
Future research should investigate the impact of thematic clustering alongside other word categorization methods on students with different foreign language proficiency levels This approach may lead to more effective outcomes in foreign language instruction By delving into this area, researchers can enhance their understanding of how these techniques can be optimally applied in language learning and teaching, catering to the diverse needs of students at varying proficiency levels.
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Declaration and Agreement of Collaboration
Ho Chi Minh City, March 1st, 2023
I am Ngo Nhat Thanh Tra, currently an IELTS Teacher of Pre-Intermediate level at Weset English Center
I have received approval from Weset English Center to conduct research on English language learning among students in the three classes I oversee: IE-Pre202212-246-1-1, IE-Pre202211-246-2-2, and IE-Pre202303-357-1.
The research, approved by the participating students, ensures that their results remain independent and separate All collected data is exclusively for my graduation thesis at Ho Chi Minh City University of Law, with a commitment to maintaining the confidentiality of the students' information.
Participants acknowledge their voluntary participation in the research and recognize that attendance does not entitle them to any benefits or compensation related to their final outcomes at the center They also agree that all personal information will be kept confidential.
I hereby committed to understand and be responsible for the above information
Observing others (Unit 19): impetuous; impulsive; pushy; taciturn; disdainful; gullible; obstinate; unscrupulous; haughty; aloof
Language of law (Unit 47): embezzlement; harassment; insider trading; joyriding; perjury; indictable; discretionary; infringe; verdict; abrogate
Colour (Unit 68): crimson; turquoise; chestnut; auburn; fluorescent; mousy; mauve; reddish; emerald; amber
Difficulties, dilemmas and hitches (Unit 72): stumbling; abstruse; arduous; convoluted; wayward; ordeal; glitch; affliction; tribulation; grueling
Permission and prohibition (Unit 75) and Complaining and protesting (Unit 76): accede; acquiesce; assent; condone; endorse; veto; clamp down; sanction; remonstrate; grouse
Diet, sport and fitness (Unit 58) and Health and illness 3 (Unit 57): plaque; buffer; offal; banish; gut; artery; stool; ulcer; ail; jaundiced
Birth and death (Unit 20): womb; Caesarean section; placenta; uterus; ectopic pregnancy; conceived; fertility drugs; foetus; fallopian tubes; fortitude
The plastic arts (Unit 26): philistinism; detractor; Tate Modern; Renaissance; fad; cubist; surrealist; deem; inured to; Impressionism
Travel and accommodation (Unit 31): apex; berth; upper deck; restriction; self- catering; chalet; inn; half board; full board; charter
Authorities (Unit 40): landing card; sniffer dog; political asylum; fixed penalty; breathalyser; surveillance; search warrant; traffic wardens; clear custom; refugee
History (Unit 44): depose; proclaim; monarchy; laws of succession; predecessor; regent; seize; corrupt; reign; usurp power
British politics (Unit 46): legislation; constituent; Institute of Director; Chancellor of the Exchequer; petition; concession; Member of Parliament; assiduously; annual climax; parliament
1 He’s so [1], I wish he would consider things first
2 [2]: stealing money that is in your care or belongs to an organization that you work for
4 [4]: something that prevents free action, progress or movement
5 The Prime Minister had [5] to demands to release secret documents about the recent war
6 [6]: unwanted substance that forms on the surface of the arteries
7 His [7] generosity led him to give away most of his money
8 [8]: making a person feel anxious and unhappy
9 [9]: greenish blue, used about fabrics, paint, sea, etc but not usually eyes
1 She’s so [1], it’s typical of her to demand an interview for the new job
2 [2]: illegal buying and selling of shares by someone who has specialist knowledge of a company
3 [3] a deep reddish brown, used about hair and horses
4 [4]: difficult, tiring, needing much effort
5 The Foreign Minister [5] in the plan to restrict imports from certain countries
6 [6]: something/someone that helps protect from harm
7 I thought he was rather [7] when I first met him He hardly spoke
9 [9]: a red-brown colour, usually used about hair
10 [10]: unreasonably long and hard to follow
1 Britain had [1] to a proposal to enlarge the EU
2 [2]: organs from inside animals which are eaten as food (brains, heart, kidneys, liver)
3 She's always been [3] of people who haven't been to college
4 [4]: for which you can be charged as a serious crime that needs a trial by jury
6 [6]: changeable, selfish and/or hard to control
7 The judge [7] the use of reasonable force by the police officers who arrested the man
8 [8]: to make somebody/something go away; to get rid of somebody/something
9 Telephone sales people often take advantage of [9] people
10 [10]: decided according to the judgement of a person in authority about what is necessary in each particular situation; not decided by rules
1 [1]: a light not very interesting brown, used only about hair
2 [2]: severe experience, which is very difficult, painful or tiring
3 The cabinet has [3] a proposal to change the way universities are funded and managed
4 [4]: tubes that carry food from the stomach
5 You are so [5] and pig-headed! Why don’t you listen when people give you good advice?
6 [6]: to break a law or rule
8 [8]: a technical problem of some kind
9 The president had [9] the plan to open membership of the club to the public
10 [10]: any of the tubes that carry blood from the heart to other parts of the body
1 He’s quite an [1] character; I should be careful if I were you
2 [2]: an official judgement made in court or at an inquest
4 [4]: pain and difficulty or something that causes it
5 The government has decided to [5] on illegal immigration
6 [6]: a piece of solid waste from your body
7 My aunt Annie can be very [7] and disdainful, but she’s lovely really
8 [8]: driving around for enjoyment in a car you have stolen
10 [10]: great trouble, difficulty or mental pain
1 Trade [1] were imposed against any country that refused to sign the agreement
2 [2]: painful infected area on the skin or inside your body
3 Barbara tends to be rather [3], I don’t know if she’s just shy
4 [4]: to officially end a law, an agreement, etc
7 They [7] with the official about the decision
8 [8]: to cause problems for somebody/something
9 [9]: to complain about somebody/something in a way that other people find annoying
10 [10]: not expecting somebody/something to be good or useful, especially because of experiences that you have had in the past
Doctors commended a mother who made medical history by giving birth to triplets, one of whom had developed outside her womb The surgeons performed a delivery via cesarean section last Friday after discovering that one baby had formed its own tissue connecting to the placenta outside the uterus, endangering the mother's life Initially, the mother was informed about her triplet pregnancy earlier on, but it wasn't until the 28th week that they identified Ronan's ectopic development, which occurs when an egg grows outside the uterus in the fallopian tubes that connect the ovaries to the womb Remarkably, the mother conceived naturally and was not undergoing any fertility treatments, as most ectopic pregnancies typically lead to termination.
Many people dismiss modern artists as merely deceiving the public, often chuckling at the more outrageous examples of contemporary art and questioning the validity of its purpose.
The current enthusiasm for modern art is evident, with attendance surpassing that of Florence's peak This interest suggests that visitors are gaining value from their experiences Historically, audiences struggled with new artistic movements, but today, acceptance of surrealism is widespread, permeating various aspects of culture, from posters to advertising Consequently, society has become more visually literate and resilient to artistic shocks and surprises.
A scheduled flight is a standard service, while a charter flight caters to a specific group traveling to the same holiday destination Charter fares typically require advance booking and provide good value, whereas budget fares are often more affordable but may come with restrictions and non-refundable policies, potentially incurring cancellation fees.
When planning your sea travel, you can choose to book a shared cabin or opt for a single or double cabin For an upgraded experience, consider a deluxe cabin, typically located on the ship's top deck, offering more space and comfort for an additional cost.
Some people prefer hotels Others prefer [6] - where you do your own cooking
When planning a holiday, travelers can choose from various accommodations, including holiday apartments, small cottages, and cabins specifically designed for vacationers In Britain and Ireland, guest houses and inns provide affordable lodging options, often at lower prices than hotels Additionally, many private homes offer bed-and-breakfast services, which typically include breakfast and one other meal, catering to diverse preferences and budgets.
On arrival in most countries as a foreigner you have to show your passport, a
When traveling, it's essential to complete a customs declaration form and be aware of potential entry requirements such as a visa and vaccination certificate Customs officials conduct random luggage checks to detect drugs and explosives, and travelers are typically required to declare items at the port of entry Additionally, customs officers monitor for illegal immigrants, including those who may be economic migrants.
For some traffic offenses you have to pay a [6], and this may be an on-the- spot-fine Parking tickets for illegal parking are issued by police and/or [7]
If there has been an accident, the police may ask drivers to take a [8] test and to make a statement at a police station
Police have limited stop-and-search powers [9] cameras operate in many public areas
A police officer cannot normally enter your home against you wishes without a [10]
Lord Acton's famous quote, "All power corrupts, but absolute power corrupts absolutely," highlights the historical context of power in Britain, where it has traditionally been held by the monarchy Succession to the throne occurs based on hereditary principles, with a new monarch taking over immediately upon the death of the reigning king or queen The eldest son of the monarch is recognized as the heir apparent, while other close relatives follow in the line of succession, designated as second, third, or fourth in line.
If the eldest son is too young to assume the throne, a regent may take his place until he reaches a suitable age Throughout history, there have been instances where a pretender has claimed that the throne rightfully belongs to him instead of the reigning king This pretender seeks to usurp the king and seize power for himself Opponents argue that such actions demonstrate an attempt to undermine the rightful ruler If the pretender succeeds, the original king can be considered to have fallen from power Additionally, a ruler who misuses their authority can be described as abusing power.