Development of DelTalk (an English Learning Application) Using Agile Method

,


INTRODUCTION
The development of information technology has affected various aspects of people's lives such as art, politics, culture, and education is no exception.The accelerated pace of globalization has facilitated the influx of foreign cultures into Indonesia and, in turn, poses P.ISSN: 2086 -4981 E.ISSN: 2620 -6390 tip.ppj.unp.ac.id the risk of future generations losing touch with their own heritage, even from an early age, potentially impacting the nation's next generation [1], [2].Over the last few years, mobile applications are no longer limited to communication purposes but are increasingly being used as important learning tools at all levels of education [3]- [5].Advances in mobile application technology have led to digital-based learning so that it can happen anytime and anywhere.In Indonesia, mobile application users have entered the world of children.This is a challenge for parents and educators who are responsible for children's education.
Mobile applications are considered effective as educational media for children because they are more practical and attractive, especially in Android-based mobile applications [6].English has become a world language that must be mastered by many people because English has dominated the era of communication to connect and transfer knowledge to the entire world [7].When it comes to the development of mobile applications for language learning, previous research tended to emphasize testing on various technologies such as multimedia, virtual and augmented reality, conversational agents and artificial intelligence-based systems [8].The results of the study [9] showed that mobilebased learning media can be applied in learning English and improving student learning outcomes.Mobile applications empower English education because they are seen as a medium that provides a large amount of information to students that teachers may not be able to supply [10].
Against this background, we were interested in creating a mobile-based English learning application that provides English learning in the form of stories called Deltalk.This mobile-based English learning application provides features in which the users can practice their speaking in English.This app was developed by integrating ASR (Automatic Speech Recognition) technology provided by NOVO Learning.The ASR was integrated with Deltalk through the API (Application Programming Interface) and Websocket.
Deltalk was developed using the Agile method.Agile is a software development method based on iterative or repetitive work, where rules and solutions that have been agreed upon by each team member are carried out in a structured and organized collaboration [11]- [13].There were several reasons why Agile was used in Deltalk development.The first reason is to do with productivity.Each team that has a different role can carry out their respective tasks without having to wait for the other team to complete their tasks because the tasks given are well structured during discussions and are carried out in parallel.The second reason is to do with communication: Agile places great emphasis on good communication between all parties involved in application development.Among the development team, design, testing and the client, intensive communication is needed within the agreed timeframe.This method is able to handle changes well and is flexible from start to finish of development.The last reason is that the targeted development time with this method is relatively fast because all teams work in parallel and problems that become obstacles are always discussed together to find solutions that are fast and good.P.ISSN: 2086 -4981 E.ISSN: 2620 -6390 tip.ppj.unp.ac.idDelTalk development was not purely agile.The development of this application adapted two agile frameworks, namely Scrum and Lean Software Development.Scrum is a framework of software development methods with an iterative concept, namely agile [14], [15].Scrum is divided into three roles: Product Owner, Scrum Master, and Development Team.
The product owner has the task of managing affairs with Stakeholders while the Scrum Master takes care of the internal part of the team and Development Team is in charge of project workmanship techniques and more detailed discussions.The Scrum method starts with a project discussion between the product owner and the relevant stakeholders, and then Scrum master and development teams are formed.When using the Scrum framework, the team must use the sprint method which is useful for creating a time limit that contains a predetermined work period and contains items or events that each team member will work on within a certain period of time.In this method, there is also a daily scrum which is held in meetings per working day of around 15 minutes to synchronize progress, discuss problems and solutions so that each process is always on time.Lean Software Development is an agile method for developing applications using minimal resources and launching applications with limited features called Minimum Viable Product (MVP) [16], [17].MVP is a product with basic and not very advanced features but has high functionality.In Deltalk development, the main goal of using MVP lies in fast product launch times, testing on real users, user feedback so that the risk of product feature failure can be minimized and save costs.

RESEARCH METHOD
DelTalk was developed using the Agile methodology.According to [18], Agile Developments methods are a group of software development methodologies that are based on the same principles or it can be said that system development in the short term requires rapid adaptation of developers to changes in any form.Agile Developments methods are fast, light, free to move and alert.In the development process, Agile is done in iterations.Agile methodology consists of several models including Extreme Programming (XP), Adaptive Software Development (ASD), Dynamic Systems Development Method (DSDM), Scrum, Crystal, Feature Driven Development (FDD), and Agile Modeling (AM) [19].DelTalk development focused on using the Extreme Programming (XP) model with the steps shown in Figure 1  Step of extreme programming [20].

RESULTS AND DISCUSSION
In this stage, the researchers performed all the stages of Agile method.Each stage was performed with the aim of achieving user satisfaction in using DelTalk.

Planning
The Planning Stage is the initial stage of data collection which was the reference for the development of Deltalk App with 1 MVP.In this stage, the researcher gathered and analyzed the non-functional and functional requirements of the users.These requirements were gathered using a questionnaire.The questionnaire was distributed to children who were currently studying at the elementary school (SD) and junior high school (SMP).The questionnaire consisted of two parts, namely the demographic and preference sections.Demographics section dealt with respondent identity while preference section was about respondents preferences of the English reading application.The questionnaire was distributed through social media such as Instagram, WhatsApp and Telegram.

Design
Figure 2 shows the Use Case Diagram of the development of the interface of DelTalk.− Selected Story: An activity carried out by the user after accessing one of the stories to be read.In this activity the user can select a list of chapters to be read and can also add books as favorite books.− Selected Chapter: An activity carried out by the user to select the exercise that will be read and executed.In this activity, users can also watch stories from videos for each chapter available in a book.− Selected Exercise: An activity carried out by the user after accessing one of the chapters he wants to read and in this activity, the user will be brought by the system to the exercise page.− Exercise: Exercise functions to train the user to hear how to pronounce a word, several words or sentences from the button speaker provided based on the illustration provided.
Then, the user can check the answers given by being able to record sound.− Get Result: At the end of the exercise, the user will get the results of all the exercises the user has done regarding the accuracy of the pronunciation of the words spoken during the exercise.− Favorite: To save a list of storybooks that the user likes on the favorites page so that accessing stories becomes faster.− Profile: An activity carried out by the user to change user data such as name, email, password settings and others.Then the user can access About Us to view the profile of DelTalk application and also access the FAQ to view a list of questions that are frequently asked by users when using the application, along with the answers.4(c-d)) and authorization system for users.The authentication process is required in Deltalk application where the system can limit who is allowed to enter the user's remote access network.To meet these needs, users who wish to access a network remotely must first be identified with authentication.where the user can hear how to pronounce a word, several words or sentences from the button speaker provided based on the illustration provided (Figure 5 (c) ).Then, the user can check the answers given by being able to record sound and the system will check the results of the recorded words or sentences given (Figure 5 (d)-(e)).Figure 5 (f) is favorite feature: if a user likes a story in DelTalk application, the user can add the story to the favorites list.6 (e) where the user can see a list containing questions that are frequently asked by consumers or the user while using DelTalk application, along with the answers.Figure 6 (f) is the implementation of the logout if the user wants to logout from DelTalk application.

Testing
In this Delltalk development, the testing scenarios are shown in Table 1: The user manages to perform the pronoun exercise DT-06-4 The user manages to reached the final level Certainly, here are the findings from the tests and their respective solutions to prevent the issues: 1. Finding: During the testing of the Login Page (DT-01-1), some users faced difficulties navigating to the registration page.Solution: To prevent this issue, consider enhancing the user interface and providing clearer navigation instructions for first-time users.Ensure that the registration option is prominently displayed and easily accessible.2. Finding: In the Home Page (DT-03-4), the "today's pick" feature did not consistently appear on the home page.Solution: To ensure the consistent appearance of the "today's pick" feature, review the data sources and scripts responsible for its content.Implement error handling and P.ISSN: 2086 -4981 E.ISSN: 2620 -6390 tip.ppj.unp.ac.id fallback mechanisms to display alternative content if the "today's pick" feature is unavailable.
These findings and their corresponding solutions should be thoroughly addressed during the development and testing process to enhance the user experience and overall functionality of Deltalk application.

Discussion
The development of Deltalk app used MVP one time.The MVP focuses on integrating ASR technology and creating multiple stories on DelTalk application.This first MVP has been completed and has been tested on real users.Testing was carried out through the User Experience Test to children around 6 -15 years.At this stage, children can see stories and interact by saying the words provided by Deltalk application, get corrections from the user's speech and get an assessment based on what they said.However, children still cannot choose a different story because the data provided was still local dummy data.The application also cannot distinguish one child from another because there is no user account system at this stage.Through the problems and feedback obtained from the User Experience Test, we suggest that for further development that there will be a second MVP that focuses on adding features, implementing the API and redesigning the appearance of the user interface.The added features include an authentication system and account authorization so that users who use this application can have their own account.Furthermore, the story which was originally still using a local database was changed to using a remote database connected via the API.Stories can also be searched by title or story description.The favorite feature is also added to the application.Users can save the stories they like on the favorites page, so accessing stories is faster.There is also a profile feature, in which user can change their personal data such as gender, profile picture and identity.When doing an exercise, the user no longer needs to press the record button again and again to stop sound recording.Improvements have been made: when the user records voice, the application can detect when the user has finished speaking and stop the recording process automatically.

CONCLUSION
We have successfully developed Deltalk application, a mobile-based English learning platform that offers a unique approach to language acquisition through storytelling.This innovative app empowers users to practice and enhance their English speaking skills.The integration of ASR (Automatic Speech Recognition) technology, provided by NOVO Learning, has been a key component of Deltalk's functionality.ASR has seamlessly been incorporated into Deltalk through the utilization of APIs and Websockets.Throughout the development process, Deltalk adopted a combination of agile frameworks, including Scrum and Lean Software Development, and implemented the Minimum Viable Product (MVP) process.The initial MVP phase involved real user testing, specifically with

Figure 2 .
Figure 2. Use Case Diagram of the interface development of Deltalk

Figure 3
Figure 3 shows the Class Diagram of the development of DelTalk.

Figure 4 (
Figure 4 (a) is the Splash Screen of DelTalk application when it is first opened.Deltalk application builds login (Figure 4(b)) and register (Figure4(c-d)) and authorization system for users.The authentication process is required in Deltalk application where the system can limit who is allowed to enter the user's remote access network.To meet these needs, users who wish to access a network remotely must first be identified with authentication.Figures (f) and (e) are the Home screen and the user can choose the story they Figure 4 (a) is the Splash Screen of DelTalk application when it is first opened.Deltalk application builds login (Figure 4(b)) and register (Figure4(c-d)) and authorization system for users.The authentication process is required in Deltalk application where the system can limit who is allowed to enter the user's remote access network.To meet these needs, users who wish to access a network remotely must first be identified with authentication.Figures (f) and (e) are the Home screen and the user can choose the story they

Figure 5 .
Figure 5.The implementation of (a) Selected Question, (b) First page of Exercise, (c) Exercise starts to Record, (d) Exercise Response Correct, (e) Exercise Response False, and (f) Favorite on Deltalk app

Figure 6 .
Figure 6 (a) is the implementation of the user profile on Deltalk, consisting of 4 main parts.These parts include profile details (Figure 6 (b) where users can see the profile details they have; edit profile (Figure 6 (c) where users can edit data (Name, Email, Date Of Birth) and Gender) from the user; change password (Figure 6 (d) where the user can change the password for Deltalk application account from the user; and FAQ (Figure6(e) where the user can see a list containing questions that are frequently asked by consumers or the user while using DelTalk application, along with the answers.Figure6(f) is the implementation of the logout if the user wants to logout from DelTalk application.

Table 1 .
The testing scenarios of Deltalk development