2.2 Review of the Related Theories
In  the  review  of  the  related  theories,  it  will  discuss  about  general  concept  of vocabulary,  general  concept  of  academic  vocabulary,  and  the  importance  of
learning  academic  vocabulary.  It  also  deals  with  language  learning  strategies  to develop  academic  vocabulary  which  covers  vocabulary  learning  strategies  and
instruction  and  academic  vocabulary  instruction.  Besides,  it  will  present  the importance of learning strategies in learning academic vocabulary and the use of
list-group-label  LGL  strategy  in  learning  academic  vocabulary  which  contains procedure in  applying list-group-label  LGL strategy and the advantages  of list-
group-label LGL strategy.
2.2.1 General Concept of Vocabulary
Vocabulary  is  list  of  words  that  have  meaning  and  several  parts  of  speech,  i.e. nouns, verbs, adjectives, and adverbs. It is very important for the students to learn
vocabulary, because learning vocabulary is the core of language learning. Coady and Huckin 1997: 5 states that “vocabulary is the central to language and critical
importance  to  the  typical  language learner.”  It  is  one  of  the  components  of
language  which contributes  an  important  role  in  developing  students‟  language
skills. Linse 2006: 121 states that “vocabulary is the collection of words that an
individual knows.” It can be defined that vocabulary is list of words or phrases that  can  be  used  to  describe  everything  in  communication,  so  we  can
communicate  with  other  people.Meanwhile,  according  to  Beck,  McKeown,  and
Kucan  2002  in  Haynes  and  Zacarian  2010:  58,  there  are  three  tiers  of vocabulary.
1 “Tier  1  includes  basic  words  or  phrases  that  do  not  need  explanation,  are
commonly  used  in  everyday  conversation  and  are  familiar  to  most  English- fluent  students.
”  In  other  words,  the  teacher  does  not  need  to  give  further description  or  explanation  for  the  students,  because  these  words  or  phrases
are easy to understand and can be find in everyday conversation. 2
“Tier    2  includes  words  or  phrases  that  are  used  often  and  included  in  a variety  of  contexts  but  that  need  explanation  because  they  are  more
descripti ve  or  precise.”  It  meansstudents  may  not  familiar  with  words  or
phrases  in  this  tier.  Unlike  words  or  phrases  in  tier  1, teacher‟s  further
explanation and description are needed to help the students to comprehend the meaning of these words or phrases.
3 “Tier 3 includes words or phrases that are not commonly used, are limited to
a particular context,  and are not  likely  to  be used outside the classroom. ” In
this tier, words or phrases are related to the specific discipline or content of a subject  and  most  likely  to  be  found  in  written  academic  text.  Since  it  is
limited to  specific fields or studies, it has low frequency to  be used in  daily conversation outside the classroom.
From  the  theories  above,  we  can  define  vocabulary  as  words  or  phrases which have meaning and several  parts of speech.  In addition,  vocabulary  is  very
important  to  be  learnt  because  it  contributes  to  the students‟  language  skills
development.
2.2.2 General Concept of Academic Vocabulary