Introduction

Academic vocabulary refers to words that can be found in academic writing from a variety of areas. For instance, academic vocabularies “which are used across content areas, have abstract definitions and are a challenge to master” (Townsend & Collins, 2008, p. 242). Academic vocabulary is described as lexical elements that are regularly and consistently employed across a wide spectrum of academic publications, such as academic journals (Coxhead, 2000).

English language learners (ELLs) all around the globe are motivated to learn academic terminology and English for academic purposes (EAP) instructors believe that doing so will help them succeed academically (Bailey & Heritage, 2008; Guerrero, 2004; Schleppegrell, 2004). Another advantage is the availability of a large number of vocabulary storage options, which allow students to be better educated and make better decisions while decoding academic materials (Honig, 2010; Schleppegrell, 2007; Shanahan & Shanahan, 2008). The development of academic vocabulary is considered so important by many teachers, in fact, that they believe their entire academic accomplishment is dependent upon it (Hakuta et al., 2000; Short & Fitzsimmons, 2007).

The selection of academic vocabulary, as well as the characteristics involved in the selection process, are an important components of effective teaching academic vocabulary. Baker et al., (2014) recommend that instructors consider the following aspects when selecting academic vocabulary: a) It is necessary in order to understand the topic; b) It can recur on a regular basis throughout the content; c) It can allow for a wide range of interpretations; and d) Prefixes and suffixes should be included.

Instructors normally place a high value on teaching academic vocabulary because they believe it is beneficial to their students, however, they intuitively disagree when it comes to defining the most successful instructional techniques to teach it. Some believe that effective use of context in conjunction with strong instructional strategies can result in successful vocabulary development (Hunt & Beglar, 2005; Nation, 2001; Webb, 2007). For ELLs to master academic language, teachers have suggested that explicit teaching is a more robust and useful strategy than implicit instruction (Norris & Ortega, 2000). On the other hand, others believe that direct education may not always be effective for ELLs (AbuSeileek, 2008, 2011; Liu, 2015). The manner in which words are presented is therefore crucial for their acquisition because it has an impact on the cognitive process (AbuSeileek, 2008). Because explicit training does not involve an increase in cognitive processing load, it may be more simply implemented in order to improve language learning (Liu & Leverage, 2017).

Theoretical Perspectives

ELLs who are adults learn best when they consciously put their effort and notice the process of the learning academic vocabulary (Schmidt, 1990). It is possible to apply the noticing hypothesis in the teaching and acquisition of academic vocabulary since the features and requirements of the two domains are so similar, despite the fact that it was originally developed for the learning of second language forms. When a new item of language is presented to the learners, they accept it intentionally and after practicing for a considerable amount of time, the declarative knowledge becomes proceduralised. Declarative knowledge provides them a clearer view of learning that eventually motivates learners to remain focused in the vocabulary learning process (Dekeyser, 2007). In Anderson (1982), Adaptive Control of Thought Model points out that learning is processed in three stages: Declarative-procedularised and automaticity. He says the first stage of learning a second language lexical needs to be explicit as it removes cognitive load from the learners. So, explicit instruction appears to be more beneficial when presenting new vocabulary to ELLs to develop their academic word stock (Laufer & Girsai 2008; Peters, 2018; Shintani, 2013). Furthermore, For ELLs, input or direct instruction plays a significant role in enhancing intake of academic vocabulary and grammatical forms, both of which are essential for success in the classroom (Lee & Huang, 2008; Smith & Truscott, 2014). According to Nation (2013), noticing can also be elicited in students if they had already encountered the term. If academic language is taught before or throughout the course, students may be better able to recognize the goal in a new context. Robinson (1995) further states that in order to notice a language trait, one must first detect it in short term retention and then rehearse it for considerable amount of time before loading it in long-term retention.

Krashen (1982), on the other hand, points out in his learning and acquisition hypothesis, and he believes that successful learning is possible even when no intervention instruction is provided. He believes that learning must be incidental and proceduralized and that any manipulation will have a long-term negative impact on academic vocabulary acquisition in the classroom. According to Long (1996), interaction and negotiation of meaning can promote noticing, which plays an important role in vocabulary acquisition by drawing learners' attention to unfamiliar language forms.. His research also found that indirect instruction was beneficial in terms of "acquisition because it integrates input, internal learner capacities (particularly selective attention), and output in a productive manner" (Long, 1996, p. 452). Leow (2015) asserts that implicit instruction is characterised by two characteristics: a lack of awareness and a low level of metalinguistic sophistication (or metalinguistic level). A similar vein, the relationship between the acquisition process and accidental learning highlights how one form of learning can be used to bridge the gap between several others, such as acquisition, incidental learning, and reinforcement learning. The acquisition process is therefore identical to what was previously described as "incidental learning" as a result of this (Ellis, 1994, p. 212).

Types of Instruction

In research, implicit and explicit instructions are treated on an equal footing with incidental and intentional learning. So, this section contains information about implicit and incidental research, as well as explicit and intentional study.

Explicit instruction involves direct and deliberate teaching of vocabulary. In this approach, the teacher provides clear explanations, definitions, and examples of new words. They may use strategies such as lectures, worksheets, and structured activities to teach vocabulary explicitly. The focus is on explicitly teaching the meanings, spelling, pronunciation, and usage of words. This approach is often used when introducing new or complex vocabulary to students. On the other hand, implicit instruction focuses on the incidental acquisition of vocabulary through exposure and contextual learning. It involves creating an environment rich in language and providing opportunities for students to encounter words naturally. This can be done through reading authentic texts, listening to authentic audio materials, and engaging in discussions or activities that require the use of vocabulary in context.

Explicit instruction

Explicit/direct instruction is a technique of teaching academic vocabulary that is well-ordered, systematic, and very useful. It is referred to as explicit teaching because it is a straightforward and transparent teaching approach that encompasses both instructional design and delivery methods (Archer & Hughes, 2011). Coyne et al. (2004) propose certain tactics for effective vocabulary training, such as direct explanation, context-rich settings, word associations, and student engagement. They emphasize the importance of explicit education in helping children develop a strong vocabulary. Zimmerman et al. (2018) showed that explicit vocabulary instruction, which involves direct teaching of words through explanations, definitions, and examples, leads to better vocabulary retention and comprehension. Students are more likely to recall and use academic language in their own work if it has been taught and reinforced explicitly over time (Nagy & Anderson, 1984). Students who receive focused instruction in academic vocabulary perform better on tests, assignments, and standardized assessments more specifically resulting in significant gains in reading comprehension (Coyne et al., 2004). Explicit instruction in academic vocabulary also benefits students' writing skills. When students have a strong command of academic vocabulary, they can express their ideas more precisely and coherently in writing (Moore, 2007). So, the explicit teaching style is viewed as a controlled approach that serves as a scaffold for learners' long-term success (Rosenshine, 1987).

It is preferable, according to Sonbul and Schmitt (2010), to explicitly teach academic vocabulary rather than implicitly teach it since it allows students to perform better in academic settings. There are a number of important activities that aid learners in the deliberate acquisition of academic vocabulary that include some common vocabulary teaching strategies such as matching printed word forms with their definitions, synonyms, and antonyms, or selecting the correct option from a list of options (Laufer & Rozovski-Roitblat, 2011). On a practical note, explicitly teaching academic vocabulary to ELLs increases their exposure time, and more time spent on vocabulary learning ultimately helps them learn more effectively (Schmitt, 2008). Because of its dynamic learning properties, implicit education outperforms explicit instruction when it comes to learning academic language for short-term reasons such as test preparation (Goo et al., 2015; Norris & Ortega, 2000; Spada & Tomita, 2010). It is assumed that pre-teaching an academic vocabulary list will be beneficial for learners who are attempting to read and comprehend academic writings such as research articles. This strategy aids students in remembering the terminology because they will be confronted with all of it in the following material (Nation, 2013). Several researchers, including Mayer (2005), have found that students who make a conscious effort to learn academic language are more likely to succeed. Rather than the tiresome process of memorizing a word list, innovative ways such as showing meaning of a word with relevant images with the support of devices can be used to teach academic vocabulary.

Implicit instruction

When an educator does not explicitly declare the objectives or explanations, this is referred as implicit instruction. Consequently, rather than lecturing, teachers simply provide knowledge or a problem to students and allow them to make their own conclusions, develop their own mental structures, and integrate the information as they see fit (Ellis, 1994; Reber, 1976).

When it comes to teaching academic vocabulary in their classes, a number of teachers use a variety of meaning-focused exercises such as guessing terms from the context or applying context clues (Chan & Leung, 2014; Graham & Williams, 2016; Marsden et al., 2013). Furthermore, it was discovered that learning academic vocabulary through uninterrupted exposure was more successful than learning academic vocabulary through explicit instruction (Kachinske et al., 2015; Leow, 2000; Rebuschat & Williams, 2012; Rebuschat et al., 2013; Williams, 2005). According to another study (Leow, 2000), that included natural setting, participants in the aware group made gains of 55 percent and 44.4 percent, correspondingly, when they were taught AV directly, whereas participants in the unaware group made gains of 5 percent and 1.8 percent, respectively. When students learn words in context, such as through reading and debating academic literature, they learn them more successfully (Nagy & Townsend et al., 2012; Tomlinson et al., 2003). Beck et al. (2002) stress the importance of giving students the opportunity to encounter and apply academic vocabulary in meaningful situations since it leads to improved comprehension and retention. Blachowicz and Fisher (2000) emphasize the importance of teaching students word-learning strategies such as using context clues and morphological analysis to aid in the implicit acquisition of academic vocabulary. According to Graves (2006), scaffolded instruction benefits pupils by gradually releasing responsibility for vocabulary learning to students, eventually leading to independent word learning. Additionally, Scott and Nagy (2004) argue that teaching discipline-specific vocabulary in science, history, or other topics should be integrated into the curriculum in a way that mirrors how professionals in those fields use these terms implicitly.

However, implicit instruction in vocabulary teaching does not need ELLs to recollect terms, which is a positive development (Krashen, 1982). This learning is also significant for a variety of reasons, the most important of which is the lack of awareness and shallowness of metalinguistic processing that occurs when students are learning academic vocabulary for the first time.

Efficacy of Explicit Instruction in Teaching Academic Vocabulary

Though there are certain basic advantages to adopting implicit education, other trajectories of explicit instruction could be more helpful in teaching academic vocabulary to ELLs since they must learn academic vocabulary quickly to be successful in academic text comprehension. Employing context cues or other implicit methods is not an option (Schmitt, 2002). Even if ELLs have a strong foundation in lexical knowledge of the target language, extracting word meaning from a written context can be a difficult undertaking. Relying solely on implicit instruction for ELLs' academic vocabulary is ineffective. If the context is unknown, even highly proficient learners may make incorrect assumptions while trying to decipher meaning. On the other hand, ELLs can get the meaning directly from explicit instruction, making it a possible solution (Lawley, 2010). Incidental or implicit instruction has been shown to be less successful when ELLs were learning the meaning and form of new vocabulary (Pigada & Schmitt, 2006). In communicative teaching, explicit instruction has been found to be more helpful in acquiring the form of the words (Long, 1991). ELLs benefit from direct instruction because they are able to connect their target vocabulary to their own language and to their own cultural experiences. A sense of belonging and motivation to take the risk of learning academic jargon are provided by this technique (Jiang, 2004). In reality learning academic vocabulary demands a high level of motivation, and exposure to the words encourages those who are interested in doing so (Tseng & Schmitt, 2008). ELLs can learn vast quantities of vocabulary and use it in academic contexts even if the lesson is crystal clear and the teaching concepts are well-planned. In addition, this helps ELLs recognize their strengths and boost their self-confidence as they progress in their academic vocabulary learning. When ELLs are presented with a list of vocabulary that is consistent and obvious at each phase of learning, they are less likely to feel overwhelmed by the demands of learning a new language (Schmitt, 2002). As a result, it is possible for students to learn academic vocabulary fast if they are explicitly instructed and motivated to do so by the sense of accomplishment that comes from having new terminology (Webb, 2007). Explicit instruction reduces students' cognitive load by encouraging them to make a concerted effort to master academic terminology and to deal with academic literature. An additional benefit of explicit training over implicit instruction is that ELLs are more likely to be successful in academic contexts and can see their progress directly when they learn academic language, which they can't do with implicit instruction (Horst et al., 2005; Joyce, 2018).

ELLs may not always have the same academic experiences and may have a different level of proficiency when they enroll in a class. As a result. many people have difficulty understanding words in context and require a great deal of practice. ELLs benefit greatly from the chance for extensive practice that comes with intentional vocabulary instruction, especially when they can work at their own pace. When they practice using academic terminology on a regular basis, they can be better able to handle academic materials and succeed (Marzano, 2004). Furthermore, regular exposure to academic terminology helps students retain it (Laufer & Rozovski-Roitblat, 2011). For learners to benefit from explicit instruction or the assistance of an instructor, they must focus on actual practice after learning the words. One effective strategy for teaching ELLs is to expose them to academic texts as soon as they learn the word (Ellis, 2001).

It has been suggested that ELLs can learn the meaning of words through word banks, computerized dictionaries, and concordances, in addition to immediate exposures to academic texts (Horst et al., 2005). Direct instruction not only presents students with assistance thinking differently, it also helps them stay on course. For students who have difficulty paying attention or remembering words learnt intuitively, this method becomes a scaffold and helps them locate the most important information through past experiences (Boers, 2004). Besides, explicit instruction has the advantage of immediately capturing the attention of ELLs, who can see their own progress and delight in the results (Ellis, 2001).

Biemiller (2001) argues that academic vocabulary instruction should be a part of an institution's policy across all grades and should begin at the beginning of an student’s academic journey so they can become more attentive and adopt the techniques as a regular and effective practice in their studies. In explicit instruction, learners with limited vocabulary knowledge can become more aware of their vocabulary development because they receive direct support and feedback. In contrast, this level of awareness may be less feasible in implicit instruction (Rupley et al., 1998). According to Biemiller (2001), the ELLs feel responsible or are inspired by seeing teachers' involvement in helping them to improve their vocabulary knowledge through this practice. As a result, they are better able to prioritize their word selections when using this method. There are some words that they do not need to remember for the future, but they might need to understand it in a specific text and they can erase those words from their memory. They can build a prioritized list of the most frequently used words if they are taught them explicitly rather than implicitly, because they will not have the opportunity to do so with implicit instruction (Goodman, 2001). Teaching ELLs the parts of speech of the words, allowing them to picture the meaning, assisting them in finding connections in their daily lives and encouraging them to reflect those in an academic environment make their learning experience more complete and beneficial (Nyikos & Fan, 2007). While this is true, it has also been suggested that English language learners may retain a considerable quantity of vocabulary if the education is clear, systematic, and consistent (Goodman, 2001).

To test ELLs' word knowledge, entertaining activities such as word puzzles and crosswords are implemented as explicit or purposeful learning instruction, and these encourage learners to devote tremendous cognitive effort in remembering words. For students' vocabulary acquisition, it is a win-win situation (Kawauchi, 2005; Saito, 2008). As a result, students who are taught academic language directly tend to score better on exams and tests than those who are exposed to it implicitly (Saito, 2008).

Explicit instruction, as shown in the preceding section, is an appropriate tool to teach academic vocabulary. Even so, its explicitness appears to be an advantage for ELLs, since it gives them additional practice time, decreases the cognitive load, and provides clear guidance and motivation for further learning. To motivate and inspire ELLs, it is important for them to be able to see the results of their efforts. In academic settings, the concept of implicit instruction is in conflict with the fact that less experienced learners cannot always deduce the meaning of an unfamiliar term from its context. Explicit instruction, on the other hand, can help learners of any language level succeed in learning academic vocabulary.

Conclusion

Explicit instruction is a systematic and structured approach to teaching academic vocabulary. In this method, teachers directly introduce words, providing clear definitions, examples, and exercises to reinforce the understanding of the terms. Explicit instruction provides students with clear and precise definitions of academic words. It eliminates any ambiguity in the meanings and usage of terms, ensuring that students grasp the concepts accurately. When specific academic vocabulary needs to be learned quickly and thoroughly, explicit instruction is invaluable. This is particularly important in scenarios where students must master vocabulary for standardized tests or for specific academic subjects. Students may quickly grasp the meanings of words with explicit instruction. Explicit instruction is highly effective for teaching complex or abstract terms that may be challenging to infer from context. This kind of instruction breaks these terms down into manageable components, making them more accessible. Teachers can easily assess whether students have learned the target vocabulary with explicit instruction since the structured nature of this approach allows for measurable outcomes.

Implicit instruction is a more natural approach to teaching academic vocabulary. Instead of direct instruction, students acquire vocabulary through exposure in meaningful contexts. They encounter academic words while reading, discussing, and engaging in real-life applications. Implicit instruction mirrors the way children acquire their first language.

Finally, studies have shown that direct instruction is a suitable instructional strategy for teaching academic vocabulary, and it greatly improves ELLs' ability to thrive in any academic context. It is, at the very least, not less useful than implicit teaching. Even if we can accept a combination of both strategies for increased ELL uptake, explanatory or purposeful instruction is also quite effective for minimizing students' difficulty in understanding academic language. In most cases, it is advisable not to focus entirely on accidental or implicit learning when developing explicit learning is critical to success as well.

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