The first part of each chapter introduces some issues in language education: what vocabulary knowledge is, what to teach, how to teach it, and how to assess it.
And I presented my research conducted to solve each topic, focusing on either the method or the research results depending on the research topic.
If you read this book with a focus on how the issues discussed in the first part are being researched in terms of the methods and practices of Korean vocabulary education research, which is the purpose of this book, it will be helpful in understanding the flow of vocabulary education research.

2.
Vocabulary and vocabulary skills

Defining what vocabulary is is not simple, but vocabulary is defined as 'a set of words used within a certain range.'
Even without following this definition, a vocabulary is a collection of words, and so the question arises: what is a word or what is a word?
The dictionary definition of the word is 'a word or similar word that can be separated and used independently.
Or, it is defined in a complex way as ‘a word that is attached to the end of a word and indicates a grammatical function’ (Standard Korean Dictionary).
If we look at the dictionary definition, it is difficult to answer the question of what vocabulary and words are because they are defined in terms of form.
Therefore, in this chapter, rather than dwelling on the definition of vocabulary, we will approach the question of what vocabulary is by examining vocabulary ability as the basis of language ability.

According to the textbook definition, lexical competence is the ability to know and use words accurately and abundantly, to infer the meaning of unknown words based on words already known, and to understand and express indicative, contextual, and figurative meanings.
Shin Myeong-seon (2008) defined vocabulary ability as the ability to express and understand vocabulary, or in other words, the ability to appropriately name an object, event, or phenomenon in a specific communication situation by considering the situation, or to understand the name that has been given.
Chapelle (1994) explained vocabulary ability by dividing it into knowledge of language and knowledge of using it in context. He viewed vocabulary ability as not only knowing vocabulary knowledge and basic processing processes, but also knowledge of the context of vocabulary use and knowledge of metacognitive strategies for vocabulary use.
Capelle explained that the factors determining vocabulary ability are the amount of vocabulary, knowledge of word characteristics, knowledge of vocabulary structure, and differences in basic vocabulary processing.
And knowing the context of vocabulary usage means not only knowing that adverbs like 'never' are always used with negative sentences, but also that in the case of '잘하다', depending on the meaning within the sentence, you can use '잘하다!' sarcastically when you did not do well, that is, knowledge of the context of usage.
This paper presents a discussion of context theory, which considers not only differences in spoken and written language, formal and informal, everyday usage and academic usage, but also differences in interpretation resulting from linguistic diversity by examining the context from a social perspective, and suggests that factors such as generational differences should also be considered.

Looking at it this way, vocabulary ability is ultimately the most crucial factor that determines language ability or communication ability, and we will move further into a discussion of vocabulary knowledge as a way to explain knowing this vocabulary.


3.
Scope and depth of vocabulary knowledge

What is all the vocabulary learners need to know? All knowledge related to vocabulary is called vocabulary knowledge, but the discussion of what vocabulary knowledge is isn't simple.
First, let's define vocabulary knowledge by looking at the discussion related to vocabulary knowledge.
Stahl (1983, 1986) divided the forms of vocabulary knowledge into two types to define vocabulary knowledge: definitional information and contextual information.
Definitional information is composed of logical knowledge between a word and other words that are already known, in other words, it refers to information such as the definition, synonyms, antonyms, and affixes of a word that are included in the dictionary.
Contextual information is defined as the core concept of a word, and is information that includes how its meaning changes in various contexts.
It goes without saying that acquiring vocabulary knowledge is achieved properly when definitional information and contextual information are learned together.

Although Nagy & Scott's (2000) study focused on how native language learners learn new words, it systematically explains what vocabulary knowledge is.
The five characteristics of vocabulary knowledge pointed out here are as follows:
First, knowing vocabulary is not a matter of knowing everything or nothing, but rather a matter of degree. In this respect, vocabulary knowledge is knowledge that increases gradually.
Research on the gradual increase in vocabulary knowledge has been discussed by many scholars.
First, Dale (1965) divided the level of word knowledge into four levels: ① words that one has never seen before, ② words that one has heard but does not know what they mean, ③ words that one can know what they mean in context, and ④ words that one knows well (re-cited from Nagy and Scott, 2000).
After that, similar studies were conducted by several scholars, and steps were added and modified little by little.
Drum & Konopak (1987) divided vocabulary knowledge into six levels: ① words that are known verbally but not written; ② words that have a meaning but cannot be expressed; ③ words that have a meaning but do not know the corresponding word; ④ words that have a partial meaning; ⑤ words that have another meaning; and ⑥ words that have neither a concept nor a word.

--- From the text