CHAPTER II
THEORITICAL REVIEW

A.	Definition of Vocabulary
In Merriam-Webster dictionary vocabulary is a list of words or of words and phrases usually alphabetically arranged and explained or defined.
According to Susan Hanson and Jennifer F.M Padua vocabulary refers words we use to communicate in oral and print language.
Vocabulary is one the fundamental aspect of language and basic communication beside pronunciation. From that statement, researcher can see that how fundamental vocabulary is. Because, without vocabulary surely human unable to produce of word and cannot communicate in orally also in print language (written). Just imagine how human could communicate if they have not vocabulary to say, how human could tell their feeling to others and how they are understand of book, novels, poems and others if they are have not vocabulary. That’s why researcher cannot underestimate this thing.
In line with Michael D Moore, Walter S Avis and Jin W Corder as cited by Ilzamudin Ma’mur and As’ari B. Fathoni in Modern English Morphology that English has a vocabulary of  well over two million words “and” a university students probably uses or recognize over 50.000 basic words.
Vocabulary is now considered as integral to just about every aspect of language knowledge. It cannot be separate among vocabularies from speaking, vocabulary from writing, vocabulary from listening, vocabulary from reading, vocabulary from pronunciation, even cannot separate it from vital area innovation such of academic approach and research.
Over the last 20 years vocabulary research has grown from a ‘Cinderella subject” in foreign language teaching and research, to achieve a position of some salience.
This fact if researcher push it to 2018 from released the book in 2007 means eleven years after the authors said vocabulary still being the salience one and surely will be the most important one. It proves from how much, how creative and how good interface application of English subject to acquire vocabulary in English now such as Memrise, Bright, Rosetta Stone etc. This is something researcher cannot deny because of developed technology in this era now even researcher want. 
Based on the definition above, the writer concludes that vocabulary is not simple thing in English learning. It has the salience beside another skills in English. This importance makes vocabulary can be related to English skills such as speaking, reading, writing and listening.
1.	Kinds of Vocabulary
According to Haycraft as quoted by Hatch and Brown (1995) divided two kinds of vocabulary, they are:
1.	Receptive Vocabulary
Receptive vocabulary is words that learners recognize and understand when they are used in context, but which they cannot produce. In line with Stuart Webb (2009) that learners recognize the vocabulary when they see and meet them in reading text but do not use it in speaking and writing.
2.	Productive Vocabulary
Productive vocabulary is the words that the learners understand and can pronounce correctly and use constructively in speaking and writing. States to Stuart Webb (2005) that productive vocabulary can be addressed as an active process, because the learners can produce the words to express their thoughts to others.
From the definition above, these kinds vocabulary has different mean which is in receptive vocabulary the learners have been taught about the vocabulary then recognize and understand it but they can’t pronounce it. Here, the learner’s looks like confusing how to use it in spoken way and just understand it in a text (context) and can’t practice it to another. Then, in the second kind is productive vocabulary which is the learners recognize, understand also can pronounce the vocabulary. This is mean that the learners not only understand about the vocabulary in a text but also in spoken way so they can use vocabulary and pronounce it to another to express their thoughts.
Jan-Arjen Mondria and Boukje Wiersma states the same that:
Receptive vocabulary learning: learning the meaning of an L2 word. Prototypically: learning a word from L2 to L1.
Productive vocabulary learning: learning to express a concept by means of an L2 word. Prototypically: learning a word from L1 to L2.
In line with Gruneberg and Sykes (1991) they divided vocabulary into two types:
1.	The first type of vocabulary refered to the one that the students had been taught and that
they were expected to be able to use. Meanwhile, 
2.	The second one referred to the words which the students would recognize when they met them, but they would probably not be able to pronounce.
It is agreed by Harmer (2001) as cited by Zunita Mohamad Maskor and Harun Baharudin (2016) that:
Has identified knowledge of vocabulary to the active vocabulary which students can use and call it orally. While a passive vocabulary of words known by learners through recognition, but they cannot call and produced through writing.
Their opinions corroborate about kinds of vocabulary in English there are Receptive and Productive vocabulary which is one another has different meaning and definition.
2.	The Importance of Vocabulary 
Vocabulary is the central of English learning because without vocabulary learners cannot express their ideas and cannot express their feelings. In line with the linguist, David Wilkins states that ‘without grammar very little can be conveyed, without vocabulary nothing can be conveyed.’
This statement means learners cannot think that only four skills in English which is important. Truly, without us knowing it vocabulary is the one that include in that four skills indirectly.
Let us look the fact, when non-native speakers went abroad something that they bring is a dictionary not a grammar books. This happened because them can use it when met the native speaker and want to ask about direction. This fact give us proof how important vocabulary especially to express our feeling to others.
States to John Read (2000) vocabulary can be seen as a priority area in language teaching, requiring tests to monitor the learner’s progress in vocabulary learning and to assess how adequate their vocabulary knowledge is to meet their communication needs.
This statement explains us another importance of vocabulary that has a function to measure learner’s progress. Especially the progress of their confident in understanding English and how they practice it. It is clear that the importance of vocabulary is not limited and pegged as an useless subject in English but also contribute to measure a progress. 

B.	Definition of Computer Assisted Language Learning (CALL)
Currently in this era, technology got the friendly of language learning. Technology being the supporter not only in government, social, and daily life human supporter but also in language learning. It could see from how much and how good the technology integrated in language learning now. Nowadays, when teacher or lecturer taught their students about the material of subject they use computer and use tools of Power Point slide explain about the material of the subject without exhausted of writing on white board. They only show the slide to the students and directly explain it to the students. So, students’ can focus on the screen which show the slide while listening their teacher explaining the material. They do not have to write it on their books and tired of writing. Many researchers suggest that integrated technology helping students in learning language. 
In line with Grimes (1977), CALL gives students a platform to learn a new language independently with minimal guidance from the teacher.
Using technology both teachers and learners are important. Because, it gave impact of language learning and minimize of teacher task to give instruction to the learners. Students can learn by themselves with little of instruction from the teacher. So, the student-centered happen and at that time teacher could focus to see the process of the students in the class. Even like that, between teacher and learner are reach the aim of the learning in that learning activities. 
According to Read (2000) he points out that computer-assisted methodologies are essential for an understanding of vocabulary that is needed to move vocabulary assessment forward. 
This research based on Read’s survey of vocabulary assessments about the computer-based Eurocentres Vocabulary Size Test and The Test of English as a Foreign Language.
For students, integrated technology could makes them enjoying the learning activities because it includes not only visual but also audio-visual. So, there is an interactive activities between the students and the technology. Beside, learning becomes more controlled, time efficiency for doing fun learning to explore students’ own thoughts and opinions about the subject they have learned
1.	The Role of Computer Assisted Language Learning (CALL)
Currently, there is a taxonomy that well known about CALL. It is from Wauscher (1996). According to Wauscher CALL divided into three stages, there are;
1.	Behaviouristic CALL
This first stage, focus on drill and practice programs like PLATO and 1980’s software.
2.	Communicative/Instrumental CALL
This second stage, described as a computer-as-tool era. 
3.	Integrative CALL
In this stage, the post-Internet era is the integrative stage, where technology is integrated into classroom practice and language learning, not separate from it. Elements of earlier stages are still found in current uses of CALL.
Based on the definition above, Wauscher states that CALL has their own stages. Like he states CALL has three stages where in the first stage is behaviouristic call, in this stage use simple drilling where teachers took an active role in helping learners select material, more learning could take place. And the popular technology at that time is PLATO (Programmed Logic for Automated Teaching Operations) that was created in 1960s at the University of Illinois and become widespread by the 1970s. In PLATO’s project, the learners did the difficult activities, and with their ability they must complete an activity (and its multiple choice test) would either allow them to move on or send them to review material.
In the second stage is communicative/instrumental CALL where in this stage we use computer as a tool era. This phase is not focus on drills but focus on more text reconstruction, language games, and programs to stimulate language use in class discussion, writing assignment and critical thinking tasks. The focus shifted from what learners did with the computer to how they worked with one another while at the computer.
Then, in the last stage is the integrative stage. In this stage CALL not only a computer as tool era was developed or only as drilling for students where they must through it in learning activity. Here, the technology being integrated in classroom practice and language learning. This means computer being the base, fundamental and primer tools of learning activities where we cannot far away from it. If we reflect it, for now maybe it is like learning activities in university where the computer, projector, speaker sound integrated as the primer of learning in the classroom and without it the presentation of material will be boring for the students in the class.
Even there are different stages, Warschauer (1996) states that the elements of behaviouristic call are still found in current uses of CALL. Because, now the PLATO system used as a special purpose programming of the subject areas of it was very board: from foreign language acquisition, math, science, and music to engineering and nursing for elementary, secondary, higher education, and workplace education. Amazingly, many modern concepts in multi-user computing were originally developed on PLATO, including forums, message boards, online testing, e-mail, chat rooms, picture languages, instant messaging, remote screen sharing, and multiplayer games.
C.	Duolingo
1.	Definition of Duolingo
A media to teaching vocabulary based on Computer Assisted Language Learning which is the writer focus on is an application namely Duolingo.
Duolingo is the best way to learn a new language. Learning a language on Duolingo is fun and addictive because lessons are split into bite-sized skills that feel like games. Learner earn points, level up, and receive rewards for progressing in the course.
According to Jaskova (2014:15) “Duolingo is seen as a future in learning languages and in global communication”. 
Beside, Paul Magnuson states that:
“Duolingo is not built as a learning management system for teachers of foreign languages to use with students, but there is obvious utility to foreign language teachers when a product is free, gamified, set up to allow one user to friend another, and comes with a discussion board for grammar and vocabulary questions.
Duolingo is popular application in Google Play store and got Google Play’s Editor Choice and ‘Best of the Best” of 2013 and 2014. Moreover, commented by the most popular newspaper The Wall Street Journal as “Far and away the best language-learning app”. And for now this application got Top Grossing Apps in fifth place. Top grossing means these apps that are earning the most revenue over a period of time.
Duolingo application was created by Luis von Ahn and his graduate student Severin Hacker and developed along with Antonio Navas, Viki Cheung, Marcel Uekermann, Brendan Meeder, Hector Villafuerte, and Jose Fuentes. This application have many different release for the user. They did private beta on 30 November 2011 and launched for general public on June 19 2012. On November 13 2012, Duolingo released their iOS app through the iTunes App Store and its free download and compatible for iPhone, iPod, and iPad devices. And finally released their Android App on May 29, 2013. 
In Duolingo, gamification poured into every lesson. Because, this application personalized learning, receive immediate grading, stay motivated with rewards and improve quickly. Called as personalized learning because Duolingo adapts its curriculum to learner’s learning strengths and weaknesses. On Duolingo, learners learn through interactive exercises, get instant feedback so learners can improve their language skills on the spot. Even they keep the learners stay motivated with rewards by earn virtual coins for correct answer, unlock new levels, and the fluency score rise. In fact, independent study has shown that 34 hours of Duolingo are equivalent to a full university semester of language courses.
In upgrade version now learners not only exercise alone but they could joining a club to exercise together with other background of learners, make some conversation, question and answer discussion and do the challenges from Duolingo. This application makes learners more active and confident to practice their target language to another learners. The challenges given by Duolingo to answer by the learners are every day with reward in it.
Moreover, Duolingo integrated to their learner electronic mail (E-mail) which is becoming reminder to exercise language every day. So, learners improve their learners’ skill every day and got their own weekly xp (experience) report and ask the learners to beat their record last week. This reminder always connected to learners’ electronic mail every day. So, learners couldn’t forget about their exercises and look for many reasons to avoid of language learning. 
2.	The Order of Duolingo Usage
Order of Duolingo usage here is for Android App. This order not too different from the PC version.
a.	Students go to Playstore in their gadget and type Duolingo in search bar. For PC version they could open it in Microsoft Store or www.duolingo.com

b.	Click Install in green bar

c.	Installing it to your gadget and choose AYO MULAI in white bar.

d.	The screen will show “Saya ingin belajar” or I want to learn in English and choose Bahasa Inggris.

e.	Choose “Pertama kali belajar Bahasa Inggris” for new English learners and choose “Sudah mengerti sedikit Bahasa Inggris” if student have known little bit of English.

f.	If you have chosen one of it, “Pilih Target Harian” will appear. This is mean you can choose your daily target based on your option.

g.	After that, the question will appear one by one. The questions that user have to answer is almost 16 questions in one rally with different questions and include four skills in it (Speaking, Reading, Writing and Listening).

h.	The screen will show green colour with text “Kamu benar” if you correct answer the question.

i.	And will show red colour with text “Ups, salah” if you wrong answer the question.

j.	“Tes Selesai” will appear and show your XP (experience). XP term commonly used in every game means experience.

k.	Usually if you did a good job you will get a gem. Particularly if you are perfect correct answer the questions in one rally.