The validity of introduction to nuclear physics e-module as a teaching material during covid-19 pandemic

During this pandemic era, learning becomes inseparable with technology. Online learning can be an alternative in using technology during the current Covid-19 condition. An example is shown through the use of Flip PDF Professional electronic module (e-module). Therefore, this research and development of an e-module on the Introduction to Nuclear Physics is carried out. This study aimed to describe the validity of the e-module developed. Research and Development method was selected for this study, and ASSURE model was further implemented with the focus on utilizing the developed instructional material. The instrument used in this study is an e-module validation sheet. The data analysis showed that the developed e-module fell into score of 83.80% which was categorized as “valid” category. Thus, Introduction to Nuclear Physics e-module is a suitable teaching material alternative during the Covid-19 pandemic. Further studies are suggested to investigate the practicality and effectiveness of this e-module.


Introduction
Without a doubt, the Covid-19 pandemic has brought serious impacts on various sectors in human life, including education. In regards with the education system affected, Indonesian government has established "Study from Home" policy to help control the spread of the virus outbreak. This applies to schools from elementary to tertiary levels. Under these conditions, teachers need to adapt to new learning systems to facilitate student learning activities [1][2][3][4]. Teachers are required to adjust to a variety of aspects, such as the ways to interact with students, types of learning media, the kinds of assignments distributed, and the teaching materials provided [5][6][7][8][9].
Introduction to Nuclear Physics is one of the compulsory subjects that must be completed by a prospective physics teacher. In this course, students learn the atomic nucleus, nuclear force, nuclear models, nuclear reactions, and radioactivity. Students need to understand these concepts, along with the various equations and calculations that accompany them. In general, learning in this course discusses declarative knowledge and procedural skills in solving calculation problems. To help students learn independently whenever and wherever, especially with the current conditions (COVID-19 pandemic), useful and engaging teaching materials needed. Teaching materials which contain not only teaching material, but also videos, practice questions, etc. Thus, electronic learning module is seen as a more suitable teaching material fitted in the current situation.
Learning module is a teaching material arranged through a systematic language which is comprehensible to students according to their age and knowledge [10,11]. Modules have selfinstructional characteristics which enable students to learn independently both at school and at home despite the minimal assistance from lecturers [12]. The modules must also contain all the teaching materials needed which provide students with the opportunity to study the material thoroughly. Consequently, the learning process provided becomes more systematic and can increase students' desire to learn and enhance their motivation [13]. Even so, the use of printed module is not efficient due to its limited access during this pandemic and that the use of papers within the modules has a potential to become a medium for virus transmission. Thus, the availability of an electronic version of the module is demanded to solve the above problems. This version is referred as an electronic module or e-module. Electronic module as a teaching material consists of educational content which are arranged systematically into the smallest learning units to achieve learning objectives that presented or published in an electronic format. The content can be in the form of audio recordings, audio visual, or interactive multimedia [14,15]. This version of the module is convenient to use as it can be accessed via internet, making it easier for students to make use of the teaching materials [16,17]. In addition, e-module is 100% paper-free as it can be read from any portable device, which makes it environmentally friendly. E-module gives learners the opportunity to be able to learn whenever, wherever, in real-time manner, through media-based Internet [18]. Furthermore, effortless access to teaching materials enable students to easily learn at their own pace [19].
One of the software used to create e-modules is Flip PDF Professional. One of the merits that Flip PDF Professional provides is that the software allows interactivity within the module, which makes learning more meaningful [20,21]. In line with these studies, another advantage that Flip PDF Professional has is that it is beginner-friendly, even to those who are unfamiliar with HTML programming language. Flip PDF Professional is a flipbook maker with the feature of editing each individual page. This software can create interactive pages in an electronic book by inserting multimedia resources such as YouTube video clips, images, audio recordings, hyperlinks, MP3 audio, flash videos, quizzes and many more [22].
Learning using Flip PDF Professional software promotes enjoyable learning atmosphere as the software allows teachers to provide knowledge through broader reference. This is in line with a research conducted by Seruni [23] which states that the developed electronic module on biochemistry using Flip PDF Professional is deemed suitable for learning and teaching purposes. Another research conducted by Sriwahyuni [15] states that developed products of electronic teaching materials using Flip PDF Professional fall into the category of a very valid teaching material quality with excellent response. Various previous studies have been conducted on integrating e-modules using Flip PDF Professional, such as Optic Geometry material [15] and Blood Circulatory Systems material [24]. However, no studies regarding the developments on e-modules for nuclear physics introductory courses have been carried out yet. Thus, the researchers believe that the urgency of this study leads the present study's aim to develop an e-module for a nuclear physics introductory course using Flip PDF Professional software. This module will be used as a teaching material during the Covid-19 pandemic. Specifically, this article will discuss the validation of the e-module being developed.

Method
This research utilizes research and development method. The final product of this study is in the form of an e-module for the introductory course to nuclear physics using Flip PDF Professional software with the use of ASSURE model. The ASSURE stages in this research consists of analyze learner, state objectives, selection of media and materials, and utilization of instructional materials. The development steps used in this research can be seen in Figure 1. The feasibility of the product is assessed through validity process. The developments of e-modules in this research utilized construct validity, which was assessed by 3 experts who were physics education lecturers with the use of a validation questionnaire.
The validation questionnaire is divided into two aspects, namely the content aspect and the display aspect. The content aspect is separated into four indicators, respectively software engineering, material organization, language, and evaluation. Engineering software is related to the functionality of the device when it is accessed using some specific hardware. An example of the functionality is the easiness in loading the program, navigation function, as well as the user interface error. Organizational indicator is related to the arrangement of the order of the materials presented in the module. Then, the linguistic indicator discusses the accuracy and effectiveness of Indonesian terms used in the module. Finally, the evaluation indicator is related to the accuracy of the formative tests given in each chapter. In addition, the display aspect is also divided into four indicators, namely visual communication, display format, attractiveness, and font style. Visual communication indicator is in connection with animation and color layout used. The format indicator assesses the components that the module should have. The attractiveness indicator discusses the accuracy and suitability of images which display information. The font style indicator relates to the appropriate shape and font size used in the module. The results of experts' judgments are expressed in percentage. The results of the validity test obtained are then categorized to the categories [25] in Table 1 below. • Analyses learner; this stage analyzes the range of students' ages, with the average age ranges from 19 to 21 years old. This age category is students fall into is known as the formal operational category. This category allows online-based learning to be applied 2.
• State objectives; the development of the e-module is adjusted to the syllabus by dividing the materials into separate chapters 3.
• Selection of media and materials; the learning media developed in this study is an emodule on Flip PDF Professional.

4.
• Utilization of instructional materials; media learning validation is developed by practitioners and academics to evaluate whether the media can be applied in the course, then, a try out is conducted in a small class and improvements are then made if experts' recommendation deem necessary. The reliability test for the three validators' assessments of the electronic module was calculated using Cronbach Alpha. The reliability coefficients obtained were then categorized [26], as shown in table 2.

Results and Discussion
The electronic module (e-module) developed will be used by students in every meeting of the nuclear physics introductory course as a reference and students' learning resource. Researchers developed the e-module which consists of a front cover, preface,  Figure 2. The data of the e-module validation test as reviewed by experts are presented in Table 3.  Table 3 shows that the average results of the e-module on the Introduction to Nuclear Physics validation aspect obtained a score of 83.80%, which fell in the very valid category. Moreover, the reliability of teaching materials gained a score of 0.89, which belonged in the very high category. In addition, the content aspect placed a higher category level than the display aspect. This is reasonable as the validator argues that the display aspect requires more revision than the content aspect. The indicators included in the content aspect are software engineering, organization, language, and evaluation, while the indicators for display aspects are visual communication, format, attractiveness, and the shape and size of the letters. The validator states that there are no revisions for the indicators of software engineering, organization, and evaluation in the content aspect. There are only a few typing errors that need to be corrected referring to the language indicator.
The display aspect requires improvements in all indicators. In regards with visual communication indicator, the validator states that the animations on alpha, beta, and gamma decay are unclear. When accessed via laptops, the animations appear too small, whereas when accessed via smartphone, the navigation panels are cut off the display. Moreover, the source from where the images are taken is not included, thus additional texts regarding the images reference shall be added. The validator adds that in the criterion of the indicator format, the sample questions given are still insufficient. The provided sample questions focus on solving problems by applying formulas. The validator argues that it will be better if the sample questions also discuss theories. Apart from the sample questions, several page numbers are not visible as they are covered. In regards with the attractiveness aspect, the cover of the module needs to be revised. The validator argues that the cover used is common and it does not contain any nuclear physics characteristics and that it tends to be similar with earth-related and space-related courses. As for the last aspect, namely the font, the validator argues that the shape and size of the letters are illegible when accessed via laptop. In addition, if it is read through a smartphone, the distance between the lines is too wide. Some parts of the module also contain uppercase and lowercase letters mixed errors. Then, the validator also asks to review the bibliography writing format. Various comments from the validator then become the main input in improving the e-module on Introduction to Nuclear Physics. The difference between the unrevised version and the revised e-module is displayed in Table 4 below.

Before After
None Educational Video

Animation Organisation
The final assessment given by the validator was in the form of criticism and suggestions regarding several technical improvements on the use of e-modules in various devices. The results of the revised final product with the use of Flip PDF Professional advance in the aspects of an attractive appearance, a tidier writing format, and a denser content. In addition, embedding videos is a distinct advancement of this e-module as students can see atomic core modeling through realistic animations. Video display provides richer information contextually than static images.
Based on the results of the validity, the average score on the content aspect is 89.44%, which is categorized as very valid. The content aspect has four points of assessments, namely software engineering, organization, language, and evaluation, all of which are categorized as very valid. Consequently, the content of the e-module developed is suitable for learning purposes. Referring the results of the average validity test on the display aspects, the score obtained is 79.16%, which is also categorized as valid. The display aspect has four points of assessment, namely visual communication,