Mizuki Moriyasu is a developing English language teacher. She studied Psychology at the Pennsylvania State University, focusing on topics such as psycholinguistics, educational psychology, and cognitive psychology. During this time, she also studied Applied Linguistics TESOL to develop more practical skills specifically in language teaching. Following the completion of her baccalaureate degree course, she entered into English language teaching at a private institution in western Japan. There, she taught learners of all ages and English proficiency levels. After a couple of years of teaching, she pursued a Master’s degree in Applied Linguistics and Second Language Acquisition at the University of Oxford. Moriyasu especially enjoys editing English writing and coaching presentation skills.

Video Abstract

Written Abstract

Vocabulary has come to be regarded as one of the most vital elements of language and language learning (Cook, 2016; Nation, 2013). In recent years, it has gained more attention in research and is being stressed more in the second language acquisition (SLA) field (Cook, 2016). In 2015, Macaro and Tian conducted an exploratory study of Chinese university professors’ vocabulary explanations in the English language classroom in an attempt to provide preliminary insight into what types of vocabulary explanation were used. This study investigates how vocabulary is explained and elaborated through a case study of two university professors at a Japanese university. Using observations of three lectures and a brief interview with each professor, this study aimed to describe the what, when, why, and how of teacher vocabulary explanation. The two observed classes were English Medium Instruction (EMI) classes, which were primarily focused on teaching content in the English language. The results seemed to indicate a tight relationship between contextual factors and how vocabulary teaching was approached (i.e., student experiences, course aims, course content, and teaching style preferences). Taken together with Macaro and Tian’s (2015) findings, this study has not only supported the need for more research on lexical explanation, but has also introduced other factors to be considered in future.

In response to recent globalization, educators have been grappling with the issue of how to efficiently induce or enhance language acquisition in on a large scale. Fueled largely by the needs of second language (L2) education, research in second language acquisition (SLA) and applied linguistics has grown greatly as an academic discipline and an informant for policy-makers, teachers, and teacher trainers. Following trends in the research and socio-political needs of language learners, L2 education has undergone much development throughout the years. More recently, there has been a push for more focus on communicative skills to facilitate actual communication in heterogeneous first language (L1) situations (e.g., business, politics, travel). Within SLA, there has been a recent surge in research on vocabulary as a core element of language competence, performance, and development. It has also increasingly been incorporated in L2 curricula. However, despite the abundance of research on lexical acquisition, development, and instruction; vocabulary learning challenges, strategies, and compensation; and lexis itself, very little has been said about teacher vocabulary explanations. This study explored non-native English-speaking teachers’ explanations of unfamiliar or unknown English vocabulary to developing English language users in an English as a Medium of Instruction (EMI) context.


The present study mainly centered on two investigative foci: (a) observing and describing teacher vocabulary explanations as a type of lexically-centered input for language learners and (b) considering how this interacted with the EMI context. The following sections will briefly present and review the literature on vocabulary instruction in language teaching contexts and on EMI as a pedagogical approach.

Vocabulary Instruction and Explanation

Types of instruction and learning. Vocabulary instruction has been discussed at length in terms of explicit and implicit instruction, both of which have also been discussed in contrast with and in terms of learners’ intentional and incidental learning. In brief, explicit instruction involves observable, overt teacher behaviors that focus on learner vocabulary acquisition (e.g., use of vocabulary lists or activities to teach specific vocabulary), while implicit instruction involves subtler manipulations of materials or behaviors to induce learner vocabulary acquisition (e.g., inclusion of target items in reading passages or modified speech). The latter was based primarily on Krashen’s (1981, 1982) Input and Comprehensible Input Hypotheses and Schmidt’s (1990) noticing hypothesis, which together suggested that learners needed to notice an unfamiliar item (e.g., through a gap in comprehension) and receive input that they could understand regarding the item in order to acquire it. From this stemmed the idea that teachers should not focus as much on explicitly teaching learners language, but should modify the input that they provided learners so that the input was noticeable (Schmidt, 1990), comprehensible (Krashen, 1981, 1982), and informative (Huckin & Coady, 1999).

While this notion has been widely supported in the literature (e.g., Ellis, 1995; Ellis & He, 1999; Huckin & Coady, 1999), other research has suggested that modified, comprehensible input alone was not as effective as that paired with explicit instruction (e.g., Paribakht & Wesche, 1997; Sonbul & Schmitt, 2010). Paribakht and Wesche (1997) reported on a series of classroom experiments testing vocabulary gains in university ESL students who were either exposed to reading and vocabulary instruction or reading only. Specifically, they tested for vocabulary breadth and depth using the Vocabulary Knowledge Scale (VKS; see Paribakht & Wesche, 1993) before and after treatment, wherein students read a passage and either completed a vocabulary exercise or read an additional supplementary passage. The findings showed that students not only gained vocabulary incidentally through reading alone, but that the gains in depth and breadth from supplementary vocabulary exercises were greater. In a similar study of 40 female medical students in Saudi Arabia, Sonbul and Schmitt (2010) also found greater vocabulary gains in learners who engaged in a reading task followed by vocabulary instruction than those who only read. Both of these studies served to further support the notion that vocabulary was gained through meaningful input, but also that such learning was enhanced by explicit vocabulary teaching.

Teacher vocabulary explanation. On the one hand, explicit instruction can be time-consuming and decontextualized, but rich in information and can induce noticing. On the other, implicit instruction is difficult to control and more nuanced, but provides context and allows for focus on developing other skills simultaneously. Vocabulary explanations, although extremely various in length, quality, and salience, are often brief (Sonbul & Schmitt, 2010), salient, and rich in specifically relevant information. In spite of comprising most of the strengths of implicit and explicit instruction, vocabulary explanation has not been paid much attention in the research literature as well as in teacher training (Macaro & Tian, 2015).

To date, only a handful of studies have directly addressed teacher vocabulary explanations in language classrooms. Chaudron (1977) pioneered the research in this area by outlining aspects of teacher talk that contributed to learner vocabulary learning. In 1982, Chaudron developed a detailed taxonomy of teacher lexical elaborations, based on observations of ESL classes in Canada, in the hopes of identifying what features of the explanations could help or hinder vocabulary acquisition for learners. In 1990, based on a survey of ESL students and teachers in Australia, Baker found that students not only desired, but expected teachers to explain unknown or unfamiliar vocabulary and that teachers were sensitive to students’ comprehension, providing many unplanned explanations when requested or evidently necessary. Following these studies, which investigated vocabulary explanation in English language classes within predominantly English-speaking environments, Flowerdew (1992) explored teacher vocabulary definitions through a corpus analysis of EMI science classes in Oman, describing frequency, dispersion, type, and salience of vocabulary explanations. Finally, stemming from research in EFL codeswitching, Macaro and Tian (2015) explored the explanatory behaviors of three experienced Chinese university EFL professors, showing a relative tendency towards either L1 only explanations or mixed language explanations. Among the three professors observed, some variance was evident in the explanatory behavior and the sample of explanations was relatively small. However, some general trends were evident, especially in language choice.

Thus far, the above reviewed studies have been extremely insightful, but conducted on a small scale. They have been almost purely descriptive and the contexts in which they were performed (i.e., time, location, course type) have been various. In response to the current trends in language education, this study hoped to contribute to a much needed area of research on vocabulary explanation through further observations. Although again presenting a new context (EMI), this study drew upon the methodology of Macaro and Tian’s (2015) study to allow for some early comparisons while providing insight into areas of interest for future studies on vocabulary explanations.


EMI in foreign language (FL) contexts, where English is not an official language, is a growing phenomenon. It is often defined by the use of English as the language of instruction, but not the object of instruction (i.e., the subject-matter that is being taught) and is identified as a means for internationalizing HE institutions and improving domestic students’ English competencies while simultaneously teaching other subjects (Walkinshaw, Fenton-Smith, & Humphreys, 2017). In response to the spread of EMI, researchers have begun to investigate the current states of EMI. Dearden (2015) conducted a study of EMI in 55 countries, using open-ended questionnaire data collected from British Council representatives across the world. She found that in spite of being in favor of introducing EMI into HE, many people are unsure of its effectiveness and what exactly it entails. Morizumi (2015) also found similar results in a study of EMI in Japanese HE, also noting concerns about both teacher and student language competencies.

Content learning is equally, if not more, important as language development in EMI. To this end, receptive vocabulary knowledge is vital, as vocabulary is one of the most crucial factors in comprehension (Nation, 2013; Stæhr, 2009). In addition, it has been argued that academic discourse requires a higher level of vocabulary knowledge than everyday discourse (e.g., Adolphs and Schmitt, 2003). Whereas language-based courses oftentimes explicitly focus on vocabulary to some extent, content-based courses typically do not, sometimes even avoiding them (Lasagabaster, 2017). In a content-based course where the language of instruction is still developing, however, how vocabulary is addressed becomes extremely important.

According to Hu and Nation (2000) and Nation and Newton (2008), a minimum of 95-98 percent of words of a given spoken text must be known for adequate comprehension. As EMI includes technical terms that are expected to be unfamiliar, it is likely that students would require knowledge of close to all of the other words used in lectures, including general and academic terms. Technical terms must also comprise less than 2-5 percent of the words used in teacher talk. Supposing that content learning is equally or more important in comparison to language development in EMI, accurate and sufficient comprehension would be imperative for fulfilling the goals of the course. This research considers how vocabulary explanations to assist comprehension and learning plays a role in EMI, where the focus on language is considerably less than that on content.

With EMI having been placed on the far end of the language-content continuum (Macaro, 2013, 2017), researchers and practitioners must consider the precise role of vocabulary and how it can be supported. Reflecting on the criticisms of explicit and implicit teaching, vocabulary explanations should be explored not only as a mode of vocabulary instruction, but also as an integral part of EMI pedagogy.

Of the various forms of vocabulary instruction, vocabulary explanations are often not directly taught or trained, but are nevertheless a common feature of many classrooms. Indeed, explanations or elaborations are a naturally occurring phenomenon in monolingual and bilingual communication, as has been demonstrated by the meaning negotiation research (Gass & Varonis, 1985; Pica, 1994). In the case of EMI, which by nature will depend heavily on students’ vocabulary comprehension for both content learning and language development, but where teachers often avoid directly language-centered instruction, vocabulary explanations may become a vital tool for success. As research specifically dealing with vocabulary explanations has been sparse, it is imperative for researchers to fill in the gaps and understand how vocabulary explanations are being conceptualized, approached, and delivered. In doing so, researchers and practitioners may gain a better understanding of vocabulary explanations as a pedagogical tool and further develop teacher training curricula and policies that address lexical explanations.


This study was an exploratory study, which aimed to describe vocabulary explanation behavior by EMI teachers. The explanatory behaviors were investigated through three research questions (RQs):

What types of words are explained or elaborated by the professors?

What types of explanations do the professors provide for novel or unfamiliar vocabulary?

How often does codeswitching occur in lexical explanations or elaborations?

To answer these questions, classroom observations were conducted followed by supplementary interviews to facilitate data analyses. Additional analyses were also conducted based on the trends found in the data.


Two female EMI professors at a university in Japan were observed three times each. For the purposes of this report, they will be referred to by pseudonyms: Tomoko (T) and Mariko (M). Both professors were L1 Japanese, L2 English speakers who had attained their Doctoral degrees in English-speaking countries and had over five years of experience teaching at the university level. Both also belonged to the Faculty of Foreign Language Studies and taught courses in Second Language Acquisition and Teaching EFL to Young Learners. The former course consisted of approximately 100 students while the latter had approximately 20-30. Both comprised mostly third year undergraduate students who had completed a year of study abroad the previous year as part of their degree course.


In order to gather naturalistic data on teacher explanations (Dörnyei, 2007; Mackey & Gass, 2005), three consecutive classes were video recorded for each professor with the researcher acting as a non-participant observer. By collecting video recordings, the data could be reviewed multiple times and more accurate transcription of both verbal and gestural explanations was possible.

Brief individual interviews of roughly 20 to 40 minutes in length were also conducted to supplement the observations and inform qualitative analyses. These were conducted in the professors’ offices following the final observation and were also video recorded. The questions, which were originally designed in English, were translated into Japanese. Prior to the interview, the professors were asked to choose the language of questioning to which the researcher-interviewer adhered so as to avoid unnecessary bias. Because the aim of the interview was to elicit as much information on the professors’ conscious decisions about and conceptualizations of vocabulary explanation, it was deemed appropriate to allow the professors to codeswitch freely to express their thoughts accurately and they were thus encouraged to use English and Japanese as they saw fit.

The collected video recordings were transcribed by the researcher and coded by both the researcher and a second rater who was fluent in English and Japanese. To investigate RQ1, word types were divided broadly into technical, academic, and general terms. Technical words were then further subdivided into strict, loose, and intention. Table 1 gives descriptions and examples for each of these word types.

Table 1 Word Types
Word type Description Examples
Technical (strict) Exact match with dictionary e.g., automatize, child-directed speech, cross-linguistic influence
Technical (loose) Related entr(y/ies) found in dictionary e.g., lexical knowledge, orthographic information, grammatical system
Technical (intention) Not in dictionary, but clearly course-content-specific e.g., mnemonic, TPO, overextention/underextension
Academic Found in AWL and not course-content-specific e.g., export, implement, prediction
Technical & Academic Any type of technical and academic e.g., implement, prediction, concept
General Not course-content-specific and/or none of the above categories e.g., cop, lark, import
Note. The examples have been extracted from the data collected for this study.

To investigate RQ2, the coding scheme used by Macaro and Tian (2015) was adapted to fit the data. As the professors did not focus on vocabulary in the traditional definitional sense, definitions and paraphrases were indistinguishable and were thus combined.

Contextualizations were extended to include those that explained the target word through example without actually using the word in the explanation (e.g., explaining “chants” as a type of activity for teaching children phonological differences between the L1 and L2 by doing a chant, see Extract 1). Finally, gestures were added to account for non-verbal vocabulary explanations through physical illustrations of the target word. The final list of codes was as follows:

  1. L2 equivalent (synonym)
  2. L2 definition or paraphrase
  3. L2 contextualization
  4. L1 equivalent (direct translation)
  5. L1 definition or paraphrase
  6. L1 contextualization
  7. Gestures
Extract 1 M: So, by using these, we can make some chants. Do you know chants? Chants is like (rhythmically taps the podium) you have the drum sound and then you going to put some phrases onto this drum sounds and then kids may be quite interested in simply comparing these two sounds. スプーンじゃなくて ((NOT SPOON, BUT)) spoon, スポーツじゃなくて ((NOT SPORTS, BUT)) sports, ナイフじゃなくて ((NOT KNIFE, BUT)) knife, チョコレートじゃなくて ((NOT CHOCOLATE, BUT)) chocolate, シャワーじゃなくて ((NOT SHOWER, BUT)) shower, チームじゃなくて ((NOT TEAM, BUT)) Students: Team.

Regarding RQ2, an additional coding scheme was added in response to a visible trend in the data. It seemed that words were not always explained for the same reasons. This became further evident when attempting to categorize the word types, as explanations for different word types seemed to hold different purposes. For example, while it seemed that “child-directed speech” was explained as a concept relevant to the course content, “cop” was explained in the context of an exemplification of a concept because it was unfamiliar to the students. Explanation purpose was thus divided into explanations of unfamiliar non-course-content-specific words explained in the traditional definitional sense (word) and in the context of an example (word for example), explanations to elaborate on a course-content-specific concept (concept), and unclear or inapplicable items. The following codes were applied to the data:

  1. Word
  2. Word for example
  3. Concept
  4. Word and concept
  5. Unclear or inapplicable

Codeswitching within vocabulary explanations was examined, as it has featured widely in L1 homogenous contexts, but has not been notably addressed in EMI. Additionally, during transcription, other trends in the data not addressed in the RQs emerged. These were further explored and additional coding was performed where necessary, namely, for explanation position. It seemed that some explanations followed the target word, while others sometimes preceded the word (i.e., labelling a concept). Explanation position (before, after, before and after, or simultaneous) in relation to the first mention of the target word in each explanation episode was coded for additional analyses.


Of the 93 total words explained in 115 explanation episodes, 91 words in 113 explanation episodes were analyzed. Two words, which were explained once each, were eliminated from the dataset because they were not relevant to the current study. One explanation was of an acronym for the university’s online student portal and the other was of an L1 word, which was translated into the L2 English. Analyses were conducted for the two professors combined and individually, as Tomoko (n = 96) had considerably more explanation episodes than Mariko (n = 17). Detailed results of each analysis have been provided in tables in Appendix A.

RQ1: Word Types

The most explained word type was technical words, when taken in combination (i.e., strict, loose, intention) and individually. Although Mariko’s most explained word type included general words, these were the next most explained word type after technical words, with purely academic words being the least explained word type. In total, technical terms accounted for 68.92% of Tomoko’s explained words and 52.94% of Mariko’s. Academic words amounted to less than 20% of each professor’s explained words, with a total of 5 words of 91 being purely academic.

From the interviews, it became apparent that this trend may at least be in part due to the EMI format of the course. When asked how important vocabulary was in their classes, both professors explained that because their courses were content-based EMI courses, they did not focus on teaching language (i.e., vocabulary). Extract 2 illustrates the professors’ conceptualizations of vocabulary’s role in their classes. In both responses, it is clear that vocabulary is viewed as an integral part of content learning, but not in itself content that must be taught. In addition, the students’ study abroad experience seemed to reassure the professors, making them less concerned about the students’ vocabulary knowledge and abilities to deal with unknown vocabulary. Mariko commented that her students generally seemed to know most academic vocabulary and Tomoko noted that having studied in English-speaking countries for the past year, her students were accustomed to learning subject-matter content through the medium of English. Lastly, Mariko mentioned that the nature of her course subject itself (Teaching English to Young Learners) did not require as much technical terminology as some other subject might.

Extract 2 T: Because it’s a content-based class, basically, students are exposed to new concepts and new ideas and then all technical terms. So, with that- that respect, making them learn new technical words is important…But not necessarily making them learn those basic words. But probably um my focus is on making them understand what I- I’m delivering. M: In order to have students understand the course content, I think it [vocabulary] is very important.

RQ2: Explanation Types and Purposes

Despite the large difference in the number of explanations, the most used explanation type for both professors was L2 definitions or paraphrases. There was some variance in the explanation types between the two professors, but overall, L1 explanations were used much less than L2 explanations and L1 definitions or paraphrases were never used by either professor. Interestingly, for both professors, gestures accounted for more explanations than did the three types of L1 explanations combined. While they were not used as frequently as L2 explanations, gestures were by no means rare, accounting for 10.53% of Tomoko’s explanations and 13.33% of Mariko’s.

As mentioned earlier, the purpose of the explanation was not always clear to the coders, resulting in some disagreement regarding the explanation type. In total, 12 explanations were marked as undecided because the two coders could not completely agree upon the explanation type. Extract 3 gives an example of an undecided explanation from Tomoko’s class. Here, “foreigner talk” is explained as “the specialized language that the L2 learners may encounter through the interaction with native speaker” and “teachers’ talk.” While the former explanation was clearly an L2 definition or paraphrase, the latter could either be interpreted as an L2 equivalent (i.e., synonym) or an L2 contextualization (i.e., example), since Tomoko refers to “teachers’ talk” as an “example.”

Extract 3 T: A little thought, um, foreigner talk – the specialized language that the L2 learners may encounter through the interaction with native speaker? Foreigner talk is um – there are different names for foreigner talk. For example, um, teachers’ talk, L2 teachers’ talk. Teachers’ talk is also an example. I mean, it’s a classroom version of foreigner talk. Foreigner talk.
Explanation purpose was determined for each explanation episode rather than each individual explanation. The most common explanation purpose seemed to be to explain a concept specific to the course content (concept). This was both in line with the reports by the two professors and the findings that technical terms were the most often explained word types, as technical terms are by nature course-content-specific.

RQ3: Codeswitching for Explanation

Codeswitching was not a salient feature of teacher explanations in the two observed courses. The total number of explanations that included codeswitching was 30, of which 4 were not explanatory (e.g., “あ、ごめん ((OH, SORRY)), sorry”). The remaining 11 explanatory codeswitches by Tomoko and 2 by Mariko were evenly divided into L1 equivalents and L1 contextualizations. A further qualitative analysis of these codeswitches revealed that most were given in or as examples to illustrate a concept. This was again consistent with the reports by the professors that they avoided the L1 as much as possible.

Additional Analyses

The additional qualitative analyses revealed several interesting findings. Particularly noteworthy was the notion of intuition, which was an underlying theme in the interviews. Both teachers initially had difficulty in identifying when and why they gave vocabulary explanations and, even after reflecting upon certain hints or thoughts that informed their behavior, concluded that a large portion of their decision-making was intuitive. In essence, they often seemed to make split-second decisions based on their immediate situations with limited to no conscious thought.

Another interesting finding was that the professors, in spite of their very different class sizes, incorporated small group discussions in their classes. Although these were not addressed in depth in the interviews, they seemed to function as a way to keep students attentive and also to allow students to negotiate meaning of unclear vocabulary and concepts, either with each other or with the professor. It also seemed to be a way for the professors to highlight key concepts for students. In terms of vocabulary explanation, on one occasion, Tomoko had given a discussion question on child-directed speech (the simplified speech used by adults when speaking to small children), which was a key topic of her lecture. During the group discussions, she was asked to clarify the meaning of this keyword several times and thus reiterated its meaning after the discussion to ensure that everyone understood.


Technical terms were most often explained spontaneously using L2 definitions and paraphrases for the purpose of elaborating or clarifying a key concept. In synthesis, the findings of this research suggested that various contextual factors influence teachers’ conceptualizations of and approaches to vocabulary explanation. These factors can broadly be separated into teacher factors, student factors, and institutional factors. In this study, the most salient factor was the EMI context, which has been categorized as an institutional factor, but could overlap with teacher factors or be a separate category altogether. This discussion goes beyond the scope of the present study and thus will not be addressed in depth.

The teacher factors that influenced vocabulary explanations have been extracted mostly from the interviews. They included factors such as teacher research background and teaching style preferences, as well as teacher intuition. While the professors in this study may have benefitted from their research in applied linguistics and their awareness of language development, other teachers without such a background may have more difficulty in identifying language-related issues and handling them. Similarly, different teaching style preferences may be more or less helpful in alleviating the linguistic burdens of EMI classes. For example, the use of small group discussions in both professors’ classes may have performed several functions such as alleviating the linguistic burden of passively listening to advanced speech, allowing for meaning negotiation and clarification, highlighting key points that may not be clear to all students during the lecture, and keeping students attentive.

Regarding intuition, as communicators, people are generally intuitive about their language, especially in the L1 (Anderson, 2000). Research has shown that modifications are made in all interactions regardless of language statuses (i.e., native or non-native) when problems in communication are perceived (Gass & Varonis, 1985; Pica, 1994). However, within L2 pedagogy, it is generally accepted that planning is both beneficial and necessary for successful teaching and learning, which is the center of much of the SLA research and teacher training. Here, again, EMI undergoes an identity crisis where it is unclear whether it belongs to the “L2 learning” category where students are developing language users, who may require linguistic support, or the “content learning” category, which assumes monolingual-like capabilities in the L2.

Student factors seemed to play a large role in teacher approaches to vocabulary explanation. Although the professors’ decisions to avoid decontextualized explanations of vocabulary seemed to be in response to the EMI setting, various aspects of the student population to which they were teaching seemed to allow them to approach vocabulary in a more strictly content-based English-only fashion. That is, the professors expressed that because the students had experienced English-only content learning during their year abroad, they felt confident that the students could manage with less scaffolding. In some EMI contexts where students may not be as experienced in English-only situations, however, more assistance may be necessary for successful learning.

Despite investigations of EMI in Japan (e.g., Morizumi, 2015) and worldwide (e.g., Dearden, 2015) indicating a lack of clear guidelines for teaching EMI in this study, the institution’s expectations seemed to impact on the professors’ teaching. Both professors noted on several occasions that their courses were EMI courses and thus did not include vocabulary learning as part of the curriculum. In addition, Mariko expressed her choice to use the L2 English even when the L1 would be quicker or easier to communicate a certain idea because of the EMI context, which entailed the institution’s as well as students’ wishes for her to conduct her lectures through the English medium. As Dearden (2015) among others has stated, it is crucial that institutions give clear guidelines for both teaching EMI and also language choice (i.e., codeswitching) in the EMI classroom, especially in L1 homogenous FL contexts.

Although the data collected for this study was sufficient for the purposes of exploring and making preliminary observations about teacher vocabulary explanations in EMI, there were several limitations which should be addressed in future research. For more generalizability, studies with larger sample sizes must be conducted, taking into account the various contextual factors that may influence the results. Although measures were taken to reduce subjectivity in data collection and analysis, the nature of several of the explored areas (e.g., explanation purpose, word type) necessitated a degree of subjectivity. In spite of the development of various lists and resources to classify technical or academic terms, no one resource exists that definitively separates words or meanings in such a way.

Furthermore, studies such as Nural and Macaro’s (submitted) investigation of technical term classifications, have demonstrated considerable variation in which words people consider to be technical, academic, and general. As was evidenced by the number of technical (loose and intended) words explained, abiding strictly by one reference list runs the risk of considerable oversight. This study was limited in that it was confined to word type classifications based on the reference resource authors’ judgments and the two coders’ subjective judgments of technicality in context. Inclusion of stimulated recall procedures could help to alleviate the bias and tap directly into the teachers’ conscious decisions.

Finally, this study did not consider student achievement as an aspect of vocabulary explanation. Given that the ultimate goal of EMI classes is for students to learn content and develop language, measures of their development in both areas would have been more informative for analyzing the vocabulary explanations, as effectiveness of explanatory behavior must also be considered.


The present study aimed mainly to explore the yet unexplored area of teacher vocabulary explanations in the EMI setting to inform future research on the subject. It also hoped to demonstrate the need for such investigation for teachers, policy-makers, and researchers. In doing so, it has become clear that there is need for more research that takes into consideration the intricate nature of teaching behavior. Not only are there various factors that account for differences in teaching, but there are also certain factors that contribute to consistency among teachers. These factors need to be identified and taken into account in teacher training programs and institutional policies. Furthermore, vocabulary explanations have been shown to vary both qualitatively and quantitatively. Although the implications of leaving vocabulary explanation research as it is are not clear, as one common source of vocabulary input, it is likely that more research in this area could potentially benefit pedagogy and language education at large.


Adolphs, S. & Schmitt, N. (2003). Lexical coverage of spoken discourse. Applied Linguistics, 24(4), 425-438.

Anderson, J. R. (2000). Cognitive psychology and its implications (8th ed.). New York, NY: Worth Publishers.

Baker, N. (1990). Teacher explanation of unplanned vocabulary. In G. Brindley (Ed.), The second language curriculum in action (pp. 93-111). Sydney, Australia: National Centre for English Language Teaching and Research.

Chaudron, C. (1977). A descriptive model of discourse in the corrective treatment of learners’ errors. Language Learning, 17(1), 29-46.

Chaudron, C. (1982). Vocabulary elaboration in teachers’ speech to L2 learners. Studies in Second Language Acquisition, 4(2), 170-180.

Dearden, J. (2015). English as a medium of instruction: A growing global phenomenon. Oxford, UK: British Council.

Dörnyei, Z. (2007). Research methods in applied linguistics. Oxford, UK: Oxford University Press.

Ellis, R. (1995). Modified oral input and the acquisition of word meanings. Applied Linguistics, 16(4), 409-441.

Ellis, R. & He, X. (1999). The roles of modified input and output in the incidental acquisition of word meanings. Studies in Second Language Acquisition, 21, 285-301.

Flowerdew, J. (1992). Definitions in science lectures. Applied Linguistics, 13(2), 202-221.

Gass, S. M. & Varonis, E. M. (1985). Variation in native speaker speech modification to non-native speakers. Studies in Second Language Acquisition, 7, 37-58.

Hu, H. & Nation, I. S. P. (2000). Unknown vocabulary density and reading comprehension. Reading in a Foreign Language, 13(1), 403-430.

Huckin, T. & Coady, J. (1999). Incidental vocabulary acquisition in a second language. Studies in Second Language Acquisition, 21, 181-193.

Krashen, S. D. (1981). Second language acquisition and second language learning. Oxford, UK: Pergamon Press.

Krashen, S. (1982). Principles and practice in second language acquisition. Oxford, UK: Pergamon.

Lasagabaster, D. (2017). The impact of the spread of English-medium instruction on Spanish universities. Language Teaching. Advance online publication. doi:10.1017/S0261444816000380

Macaro, E. (2013). Defining and researching English Medium of Instruction: The need for clear thinking and a clear research agenda. In British Council (Ed.), British Council Regional Policy Dialogues 2013-14 (pp. 23-27). Retrieved from https://www.britishcouncil.org/sites/default/files/bc_regionalpolicydialogues_baja.pdf

Macaro, E. (2017). English medium instruction: Global views and countries in focus. Language Teaching. Advance online publication. doi:10.1017/S0261444816000380

Macaro, E. & Tian, L. (2015). Exploring teachers’ oral explanations of new English lexical items in a Chinese university: Comparisons with dictionary information. System, 52, 78-90.

Mackey, A. & Gass, S. M. (2005). Second language research: Methodology and design. Mahwah, NJ: Lawrence Erlbaum Associates.

Morizumi, F. (2015). EMI in Japan: Current status and its implications. Educational Studies (International Christian University), 57, 119-128.

Nation, I. S. P. (2013). Learning vocabulary in another language (2nd ed.). Cambridge, UK: Cambridge University Press.

Nation, I. S. P. & Newton, J. (2008). Teaching ESL/EFL listening and speaking. Abingdon, UK: Routledge. Nural, S. & Macaro, E. (submitted). Vocabulary in an English Medium Instruction context: Selection and difficulty.

Paribakht, T. S. & Wesche, M. (1993). The relationship between reading comprehension and second language development in a comprehension-based ESL program. TESL Canada Journal, 11(1), 9-29.

Paribakht, T. S. & Wesche, M. (1997). Vocabulary enhancement activities and reading for meaning in second language vocabulary acquisition. In J. Coady & T. Huckin (Eds.), Second language vocabulary acquisition (pp. 174-200). Cambridge, UK: Cambridge University Press.

Pica, T. (1994). Research on negotiation: What does it reveal about second-language learning conditions, processes, and outcomes? Language Learning, 44(3), 493-527. Schmidt,

R. W. (1990). The role of consciousness in second language learning. Applied Linguistics, 11(2), 129-158.

Sonbul, S. & Schmitt, N. (2010). Direct teaching of vocabulary after reading: Is it worth the effort? ELT Journal, 64(3), 253-260.

Stæhr, L. S. (2009). Vocabulary knowledge and advanced listening comprehension in English as a Foreign Language. Studies in Second Language Acquisition, 31, 577-607.

Walkinshaw, I., Fenton-Smith, B., & Humphreys, P. (2017). EMI issues and challenges in Asia-Pacific higher education: An introduction. In B. Fenton-Smith, P. Humphreys, & I. Walkinshaw (Eds.), English medium instruction in higher education in Asia-Pacific: From policy to pedagogy (pp. 1-18). Cham, Switzerland: Springer.