The use of Duolingo to Assist EFL Students of Prof. KH. Saifuddin Zuhri State Islamic University in Learning Vocabulary

Vocabulary is one of the important aspects in the process of learning English. It is a basic component of the four main language skills that can improve one's mastery of English. There are many application media for English which can help students in learning activities. This study used the Duolingo application as the object research. The purpose of this research is to investigating the implementation of the Duolingo application to assist EFL students of State Islamic University Prof. K.H. Saifuddin Zuhri Purwokerto in learning vocabulary. In this study, researchers used qualitative data analysis techniques to obtain actual data. The method used to analyze the data is thematic analysis in order to gain experiences, views and opinions of participants in using the Duolingo application. For collecting the data, researchers used observation and interview. The finding of this study were about the perceptions and students interest towards Duolingo application as learning media which assist them in learning vocabulary. It revealed that most of participants gave positive statements about the Duolingo application they used. they think this application helps them in improving vocabulary especially when they as beginners. Some of them also gave statements that Duolingo would be a tedious application to use when the learner have a great vocabulary level.


INTRODUCTION
In this modern era, English is increasingly needed and also more used in various aspects. Vocabulary is one of the crucial aspects in the process of learning English. Roche and (Harrington, 2013) as cited in (Dakhi & Fitria, 2019) argued that knowledge of vocabulary is a prerequisite for language skills. Many Indonesian EFL students have difficulties in mastering vocabulary. According to (Masita, 2020), teaching vocabulary is a challenge because English is not the first language in Indonesia. Moreover, the position of English in Indonesia is a foreign language, so that the application of English is not optimal which makes it difficult to learn, because most EFL students only focus on textbooks in the class. In contrast to other countries that have used English as a second language which also used it in they daily life.
The purpose of learning vocabulary is to improve mastery of English, because vocabulary is a basic component of the four main language skills. According to (Alharti et al., 2020) the four language skills are: reading, writing, speaking, and listening. Therefore, learning vocabulary can help in mastering English and make them able to apply it in they daily life, such as when they read English text, speaking, etc. (Apdy & Asrifan, 2018) state that in a language, vocabulary always be the main element. It show that vocabulary mastery is one of the points that determine the success of EFL students' mastery of English.
Furthermore, technological developments thrive in various aspects of life, one in education. Many applications based on mobile learning have been created that can be used as learning media. (Nursyamsiah, 2021) Mobile learning makes education available flexible in terms of time and place and can alter students' perceptions of learning. (Irawan et al., 2020) stated that learning English with a mobile application is one of the creative and systematic efforts that can stimulate interest in learning and create new experiences for students. Many teachers try new innovations to improve student learning in English especially in increasing students' English vocabulary which one is with application. There are many applications in English, one of the existing applications is Duolingo application.
Duolingo is one of the most popular apps that can be used by many circles. Duolingo can help teachers and students in the learning process. Duolingo is an app designed to help students learn language easily and with pleasure so that students do not feel forced to learn but enjoy the learning process. (Jovaska, 2014) as cited in (Wijaya et al., 2016) points out that Duolingo can be used as a global language and communication media in the present and future. According to (Tiara et al., 2021) Duolingo has a very good and inspiring way of learning when used. This application calls lessons with games that build students' morale in learning. The Duolingo application combines visual audio and interesting questions that students can enjoy primarily in the vocabulary study bowls.
According to study that conduct by (Irawan et al., 2020) which analyzed the use of the Duolingo application as an English learning medium, they found that learning activities with Duolingo had not fully achieved the expected targets and results, but could make teaching and learning activities more effective and varied as well in improve students' ability in speaking English and their vocabulary mastery. Meanwhile, (Jaelani & Sutari 2021) more focus on the perception of whether students are interested in using the Duolingo application, and they find positive perceptions from students that this application is quite interesting because it is easy to use in learning English and can be used anywhere and anytime. In line with that (Tiara et al., 2021) explains the students' perceptions of using Duolingo as vocabulary learning applications that are positive effects of which are encouraging students in improving English skills, both convenient and fun. (Aulia et al., 2020) compared students of eighth graders at SMP Jember in the academic year 2019/2020 which teach by Duolingo and not, they found had significant results and showed that students who were taught using Duolingo had better grades than those who were not. The use of Duolingo applications can improve the student's listening capabilities and can also make teachers submit student motivation in learning English (Putri & Islamiati, 2018).
Based on the statement above, vocabulary is an essential component of language learning that has to be mastered by EFL students in Indonesia. EFL studies at State Islamic University of Prof. K.H. Saifuddin Zuhri Purwokerto can make good use of the technological development, one of which is Duolingo applications. Hence, this research focuses on investigating the implementation of the Duolingo application to assist EFL students of State Islamic University Prof. K.H. Saifuddin Zuhri Purwokerto in learning vocabulary.

Vocabulary as the main component of English
Vocabulary considered as the head from language. Vocabulary is a principal and vital thing in language teaching and language learners. (Susanto, 2017) stated that vocabulary was the first basis for learning a foreign language. (Neuman & Dwyer, 2009) as cited at (Alqahtani, 2015) stated vocabulary as words that must be known for someone to communicate effectively: words in speech (expressive vocabulary) and words in listening (receptive vocabulary). Mastery of vocabulary is important in learning English. According to (Zahedi & Abdi, 2012) as cited in (Irawan et al., 2020), their writing research states that one of the components to mastering English as a foreign language is vocabulary mastery. From this statement, it can be concluded that vocabulary mastery is the key in learning a language, and it means that without studying the vocabulary, the students would be impossible to communicate effectively.

Teaching Media for Effective Vocabulary Learning
Media is informative introduction to the tool from the information owner to the recipient information. Media is a tool used by teachers in the teaching and learning process to facilitate and provide teaching materials to students. According to (Arsyad, 2011) Learning media is everything that is used as a learning resource and can be used to convey messages from sender to receiver so that they can feel interest, curiosity in such a way that the learning process takes place and further explained that learning media is a tool in the learning process both inside and outside class (Irawan, 2020).
In addition (Kusumadewi, 2018) Stating there are 4 types of learning media, namely audio media, visual media, audio media and multimedia. Visual media is media that uses vision (eyes), for example graphics, tables, PowerPoint, pictures.. Audio media only uses hearing, for example, radio, LPs, recorders . Audio Visual Media is media that uses sight and hearing in an activity process, for example video. Multimedia Is media that involves several types of media and has integrity in learning.
According to (Kusumadewi, 2018) the many benefits of using media in the teaching and learning process. Using interesting learning media will enlarge and increase students' curiosity with the learning media presented. The learning media can overcome the differences students based on economic background and students' ability to try earn through experience and reality, Teaching media can help students in understanding difficult learning. Learning media can help students' minds regularly develop about what they experience in their teaching and learning activities, such as: watch a film about an events. The sequence of their event watched and screened films will be studied regularly and continuous basis. Based on the statement above, it is concluded that the types of media that can be applied in learning are very diverse and use the media according to the needs of students. Various kinds of learning media will help students in honing their interests and talents.

Duolingo in Vocabulary Learning
Duolingo was created in 2010 and was originally created as an online web which then continues to grow, evolved to become available on Android and IOS (Duolingo, 2016). From Teske, (2017) Duolingo is an free application created to facilitate online learning of various languages which was created by Luis von Ahn and Severin Hacker and was launched in 2012. Duolingo itself considers as a personal language tutor, users of the application can learn the language independently by following the instructions given by the application which will build the motivation of users through various activities provided such as games that are nothing but a language mastery booster (Duolingo, 2011).
At the beginning of using the application you will be given a questionnaire to find out what level you are, because the material that will be given is adjusted to your level. Then to increase the level there will be exercises given that are arranged as attractive as possible. There is various exercises that will be given that is translation exercise, here you will be given exercises to translate a language they want to know into a language they know or vice versa. Matching exercise, here you will be given an exercise by displaying a photo, then you are asked to match it with the words given or vice versa. Pairing exercise, here you will be given a complete sentence from both languages, then you are asked to pair the words from the sentence so that it is arranged correctly. Listening exercise, here you will be given exercise to listen to phrases in a second language, then you will be asked to type them correctly. And the last is speaking exercise, here you will be given a word or sentence, then you will be asked to say it in order to know your speaking ability.

METHOD
This research utilized qualitative research design. To complete this research, the researcher applied case study method. (Creswell, 2012) stated that qualitative research not only determines whether you will observe or interview the respondents but also to know the perceptions of the respondents regarding the use of Duolingo in the vocabulary mastery process.
The subject of the research are students 2nd and 4th English Department in State Islamic University of Prof. K.H. Saifuddin Zuhri Purwokerto. Because this research about the perception of the applications of Duolingo learning vocabulary so, the object of this research are students English education students who study in State Islamic University of Prof. K.H. Saifuddin Zuhri Purwokerto who they are use the application to learning vocabulary and they are 10 respondents who use application duolingo : The techniques used for collecting the data in this research are observation and interview. In the entire process of the observe, the researcher will investigate the implementation of EFL student's vocabulary in State Islamic University of Prof. K.H. Saifuddin Zuhri Purwokerto to find out how much influence the Duolingo app has on them. The researcher also do some interview with the students of State Islamic University Prof. K.H. Saifuddin Zuhri Purwokerto students which is using Duolingo app on their android phone. Moreover to get the data that the researcher wants, the researcher will also participate in activities in the setting that the researcher observes.
This study uses qualitative data analysis techniques to obtain actual data. The method used to analyze the data is thematic analysis in order to gain experiences, views and opinions of participants in using the Duolingo application. So, after collecting data from the results of interviews with participants, the main points of several questions in the interview will be grouped to get the main data that will be the discussion of our research.

Students' Interest towards Duolingo Application
From the data collected by the researchers, it was found that 60% of respondents were interested in using the Duolingo application because the appearance of the Duolingo application, both the layout and looked attractive. 30% interested because introduced by a friend. And 10% for trying multiple language learning apps at once. In addition, it was found that 60% of them are no longer using the Duolingo application and 40% are still using the Duolingo application until now.
The first respondent used the Duolingo application for approximately one year, and he stated that he initially chose Duolingo as a learning companion application because of the attractive and simple appearance of Duolingo. He said that after first trying the Duolingo application, he found it helpful in his independent learning and then later used Duolingo as a learning companion application. This can be seen from his words, namely:

"I choose to use duolingo application because the layout looks so good, so I try to use it and I like it". (R1) "I think this application is very helpful in improving vocabulary and is fun. Vocabulary obtained after using the Duolingo application can be used in daily activity". (R1)
The second respondent has used the Duolingo application for two months and is still using it. Just like the first respondent, the second respondent also uses the Duolingo application because of its attractive appearance, he said that the application is very helpful in improving English vocabulary.

Features in the duolingo app
In interviews conducted by researchers, one of the objectives was to find out the features in the Duolingo application used by respondents and make them use the Duolingo application as a learning companion application. From interviews conducted, it is known that the Duolingo application has various interesting features, such as achievements, lingots, levels, daily goals, to club networking. R7 who has been using Duolingo for a year said that he liked the level system of the Duolingo application because it was very helpful for learning gradually according to his ability and he also liked the tasks given and the daily targets that prompted him to use Duolingo as a study companion application.

"After using this duolingo application, it has improved considerably, since its vocabulary starts at a very basic level, and vocabulary can be used in daily life and can apply it gradually". (R7) "I like duolingo application because the achievements and daily goals that make me enjoy and want to clear the achievements and going to the next level". (R7)
In addition, R3 said that what makes Duolingo even more interesting is because its have much cute avatar, various games, and also because the features are not only intended for learning English, but can also be used for various other languages. Some of the features mentioned above can be seen in the following images: Pictures from left to right: choice of language, independent level, public ranking, lingot.

The benefits of using the Duolingo application as a companion application in learning vocabulary
The researcher found that 90% of the respondents agreed that the Duolingo application provided benefits in learning to improve English vocabulary. While 10% stated that the application was less helpful.
"Duolingo's application is the one application that recommended to someone who wants to increase the number of vocabulary. It is because the fitur in this application drawing feature that made us easy and happy to use it so we could not easily to get bored." (R7) "Yes it (duolingo) is fun, because in upgrading levels there will be reward that make me motivated to continue using it. And it simple because I just need to open my handphone then playing it". (R4) "The achievements and the daily goals in duolingo app is very help me as beginner in learning English especially in vocabulary like choose the right answer that switch with the picture also the translation exercise ". (R3) From the statements above, it shows the benefits of the Duolingo application such as from its helpful features especially for beginners. The simple content from duolingo also make users easy to understand so its easy to use. The application also convenient to be a study assistant application because it can be used anytime and anywhere. However, someone whose language level is already high will quickly feel bored because they find it easy to complete the tasks provided. As stated by R8: "I only used Duolingo for a month, at first I used it quite often, then the following days it was very rare because I found it too easy and less challenging". (R8) The benefits of duolingo according to what the researchers found can be seen in the following table:

DISCUSSION
The results of the data collected by the researcher show that some students are interested in using the Duolingo application both for its appearance and content. Because of its attractive and simple appearance, the Duolingo application is used as a learning companion application as well. This application helps increase vocabulary and is easy to use and fun. The results of this study are also in line with previous research by (Tiara et al., 2021), which explains the students' perceptions of using Duolingo as a vocabulary learning application, the positive effects of which are encouraging students to improve their English skills in convenient and fun ways.
Based on the findings, the researcher discovered some misconceptions about Duolingo's use as an effective assistant application for English learning vocabulary. The respondents had an argument that they felt it was easy to use Duolingo in learning English and that it could be used anywhere at any time, so they could easily understand and study English vocabulary. In addition, it was also found that respondents used interesting features such as achievements, lingots, surveys, daily goals, and also club networking. That helps them to learn English vocabulary. This application offered some features, materials, and study tests. This application provides a lot of vocabulary as well as grammar that can help students correct English sentences. This application also includes many pictures to support the learning process. The findings indicate that students are generally quite enthusiastic about the use of the application and can greatly enjoy the flexibility and practicality of the application. These findings reinforce the fact that much literature highlights the potential and positive responses to language learning through mobile phones (Morris et al., 2012). Duolingo is effective as application assistance for teaching vocabulary. (Mulya & Refnaldi, 2016) claim that the Duolingo application motivates students to proceed and exceed their previous record in this application. On the other hand, students are enabled to compete with their friends. The students can earn experience points (XP) across different levels, and then they deserve lingots with which they can obtain items and bonus lessons. Duolingo can be accessed on computers and also on Androids by downloading it from the Play Store. The interface is clear and simple to use. There is also a charming balance between translation, listening, matching, and speaking exercises. The voice recognition program is also good. On the other hand, this statement contradicts with the journal of Finardi, Leo, and (Amorim, 2016) that states, despite the potential of MALL in general and Duolingo in particular, there is still improvement and adaptation required to use mobile devices out of class and inside classes as additional support to language learning. Therefore, schools and teachers need to find alternative ways to utilize this technology in order to encourage interaction and learning in improving English, especially in learning vocabulary.
In addition to the benefits of using Duolingo as a vocabulary learning assistant application, the researcher found that more students felt the benefits of Duolingo than those who did not. The results of this study are the same as that of (Miftakh & Yulianti, 2021) who stated that in their research on the perception and experience of secondary students in using Duolingo, they received positive responses from students where they felt facilitated to learn vocabulary using Duolingo. Where in the study both used interviews to obtain the data needed in the study and found that most of the respondents in the study stated that they felt the benefits after using Duolingo. (Gilson et al., 2012) stated that the Duolingo application provides benefits to students so that they get the opportunity to practice their language continuously because Duolingo is available and can be accessed anytime and anywhere. The findings from that study have similarities and differences where in our study we found that Duolingo is comfortable to use because it can be used anywhere, but for people who have a high level of language, they cannot feel the benefits of Duolingo because it is too easy for them to complete tasks that are required given.

CONCLUSION
This research is an attempt to explore the perceptions and experiences of students in the 2 nd and 4 th English Departments of State Islamic University Prof. K.H. Saifuddin Zuhri Purwokerto about using Duolingo as an assistant application in vocabulary learning. In this study, there are three main topics, namely regarding students' interest in the Duolingo application, features in the Duolingo application, and the benefits of using the Duolingo application as a companion application in learning vocabulary. We know that vocabulary is the main component in language learning, but in order to provide convenience and good facilities, we can take advantage of technological developments. With this in mind, the researcher found out what Duolingo could do to help students learn vocabulary with the rapid development of technology. This research is utilized using research design. To complete this research, the researcher applied the case study method. Due to limitations in the research we did, for the respondents we collected data from, there were 10 students from the 2 nd and 4 th English Departments in the State Islamic University Prof. K.H. Saifuddin Zuhri Purwokerto. From the findings and discussion, it can be concluded that Duolingo can help students learn vocabulary if we look at the results of interviews with each respondent. They show an interest in using Duolingo as an application they use to help them learn vocabulary. Duolingo has various kinds of features that can help students learn well. But on the other hand, this application still has several weaknesses, namely that there must be a good internet connection in order to operate properly. And for university students, the vocabulary in Duolingo is still fairly basic, so it's not enough to help learn new vocabulary.