Integrating English Subject Materials into Islamic Boarding School Curriculum Context: Insights from Aceh, Indonesia

Issues surrounding curriculum integration have been discussed worldwide. Some argue that curriculum integration contributes meaningfully to empowering students’ multi knowledge and skills, while others claim that curriculum integration has detrimental effects on teachers and students’ study load. This qualitative study investigates the English teachers’ and Islamic boarding school principals’ perceptions of integrating English subject materials of Curriculum 2013 into the Islamic boarding school curriculum context. Eleven participants (two Islamic boarding school principals and nine English teachers teaching at two Junior Islamic boarding schools in Banda Aceh) were selected purposively. The findings indicate that integrating English materials into the Islamic boarding school curriculum positively contributes to developing students’ general and Islamic-related knowledge. The results also suggest that the integration of English materials into the Islamic boarding school curriculum can be performed by switching the listed materials in the syllabus of Curriculum 2013 with the Islamic-related materials. The study unveils that among these curricula integration challenges are the inadequacy of Islamic-related knowledge that the teachers master and the subject overload. These two main issues are the main challenges to integrating the English materials into the Islamic boarding school curriculum.


INTRODUCTION
The integrated curriculum is the most popular way of designing primary education curricula (Fraser, 2000;Ollila & Macy, 2019). It is believed that curriculum integration may increase students' engagement in the teaching and learning process, further helping them synchronize information connected with their prior knowledge and experiences (Niemelä, 2021). In addition, this curriculum integration ensures that the teaching and learning process is relevant and related to students' lives in the real world (Beane, 1996;Rennie et al., 2011). Throughout this curriculum integration, several essential concepts and skills can be taught meaningfully and interestingly to students.
Curriculum integration is one of the educational approaches which lays the foundation for lifelong learning for students (McPhail, 2018). Its teaching and learning approach involves a combination of subjects, establishes a relationship among concepts, emphasizes projects, and utilizes teaching and learning sources beyond textbooks (Akib et al., 2020). In addition, according to Brown (2016), curriculum integration engages students as active learners who make the most of their decisions about what they study.
In the context of Indonesia, an integrating curriculum can be carried out as long as the local content curriculum follows the existing rules and still refers to the National Education Standards. Nevertheless, an integrated curriculum may have a specific meaning for certain educators. This may mean connecting one subject to another or dynamically engaging various subjects to show their correlation.
Nowadays, Islamic boarding school institutions cannot be separated from the Muslim life in Indonesia (Ali, 2019). Islamic school institutions thrive throughout the Indonesian archipelago, including in Aceh. To ensure that the schools fulfill the national government's educational service and quality requirements, Islamic boarding schools integrate Islamic values into their national-based curriculum.
Islamic boarding school curriculum focuses and emphasizes religious studies and science. This integration enables the students who are learning at Islamic boarding schools to master Islamic-related knowledge, and at the same time, they also master sciences. The trend of integrating science and general knowledge into Islamic boarding schools in Indonesia has increased in the last few years (Azis & Anwar, 2016;Muhammad, 2017). The integrated curriculum is expected to influence lesson planning and become a reference for curriculum design so that individuals can personally and socially interact regarding essential issues (Beane, 2016;Hudson, 2012a).
In Aceh, the number of students studying at Islamic boarding schools increases significantly. This phenomenon is reasonable because the province of Aceh implements Islamic law in which its educational core is based on the Quran and Sunnah (Hadits) values (Habiburrahim, 2018;President of Republic of Indonesia, 2006). Most parents in Aceh consider that studying at Islamic boarding schools may give their children an excellent opportunity to learn general and Islamic education. Parents believe that studying general and Islamic education enables their children to master the sciences and possess good moral characters (Muluk et al., 2019). Curriculum 2013, in addition, provides an excellent opportunity to prepare students to obtain knowledge that meets the Acehnese educational core values.
While extensive research has been conducted exploring curriculum integration, there was a paucity of empirical studies carried out in integrating English teaching and learning materials into Islamic education, particularly at Islamic boarding school institutions in Indonesia. As such, this current research intends to fill in this research gap by answering the following questions: • What are the teachers' opinions about curriculum integration? • How do the English subject materials of Curriculum 2013 integrate into the Islamic boarding school curriculum? • What are the challenges in integrating English subject materials of Curriculum 2013 into the Islamic boarding school curriculum? Thus, the perspectives of the English teachers and heads of Islamic boarding schools regarding curriculum integration, the ways to integrate the English subject materials of the Curriculum 2013 into the Islamic boarding school curriculum, and the challenges of integrating the English subject materials of the Curriculum 2013 into the Islamic boarding school curriculum served as the major investigation of this study.

Curriculum Integration
Integrating a curriculum is an effort to unite a curriculum by combining two different curriculum contexts that can enrich the teaching and learning quality. McDowall and Hipkins (2019) mention that curriculum integration provides chances to connect diverse subjects. It intends to develop a more efficient curriculum delivery and offer students a more meaningful learning experience. In addition, curriculum integration has the potential to become a way to show students how similar abilities or skills may be applied across different disciplines. Curriculum integration is generally part of a more comprehensive set of educational practices involving inquiry-based learning and other types of learning that make use of time flexibility and cooperative teaching across various levels of classes (McDowall & Hipkins, 2019).
Integration of the curriculum emphasizes learning arrangements and approaches that can establish a good connection with a lesson being discussed between a teacher and students (Long et al., 2010;Murdoch, 2015). Such a perspective corroborates the idea of the integrated curriculum becoming a way of creating better and more meaningful education. In addition, an integrated curriculum may also become an effective approach in helping develop relevant and manageable education. It has advocated a constructive view of learning. Additionally, as it helps students prepare for lifelong learning curriculum integration, every school should perceive education as one way of learning skills students need, particularly when facing modern life challenges, rather than a separate and segmented discipline (Akib et al., 2020). Habiburrahim,Muhammad,L. Auni,Hafidhah & I. K. Trisnawati,Integrating English subject materials into Islamic boarding school curriculum context: Insights from Aceh,Indonesia | 670 From the Islamic perspective, it is expected that the integration of the curriculum at Islamic boarding schools may nurture students not only to be Muslim intellectuals who have noble characters and are pious but also to be scientists and technocrats who could always stand at the forefront of Islamic community development (Muhammad, 2017). In the same vein, Muhammad (2017) adds that integrating Islamic values into general knowledge or science aims to encourage people to not separate science and religion, the world and the hereafter, technology, and ethics, and race and skin color. Islamic scientists are expected to have a noble character to get a high predicate, both in the eyes of humans and in the sight of Allah. According to Istikomah (2017), the integration of science and religion, particularly at Islamic boarding schools, cannot be carried out formally by justifying the verses of the Qur'an on every scientific discovery or only by connecting the verses of Allah with science that has long been studied and applied by humans in the order of life in this universe. The most important thing is a paradigm shift based on understanding science to suit the Islamic scholarship related to metaphysical, religious, and sacred texts.

Islamic Boarding School Curriculum
In the context of Islamic education, the Islamic educational philosophy proposed by Al-Faruqi (1989) follows the values of the Qur'an and Sunnah (Prophet Muhammad tradition), which reflects the principles and the spirit of Islam that constitutes its view upon the essence of education. Al-Faruqi significantly influenced the development of higher education in the Islamic world, which reflected his ideas and vision (Rahman et al., 2015).
According to Kazeem and Balogun (2013), Islamic education is complete and all-inclusive since it embodies all religious-related and secular-related knowledge disciplines. Thus, Islamic education should improve the healthy development of a human's whole personality by training the spirit, intellect, rational self, emotions, and physiological senses (Kazeem & Balogun, 2013).
Conferring to Zarkasyi (2015), nowadays, Indonesia's Islamic boarding schools employ a modified curriculum befitting the curriculum that simultaneously emphasizes Islamic-related subjects and a modern instruction method. A wellincorporated curriculum within the Islamic education system can help generate students with a stable and balanced soul (al-nafs), intellect, and emotions for a better future generation (Rosyad, 2020;Shalihin et al., 2019). To this end, the curriculum should be well prepared, involving thorough planning and paying close attention to specifics and functional issues.
Islamic education has recognized that there is no knowledge segregation. Islam regards science and Islamic-related knowledge as two inseparable entities that all Muslim scholars should master. Silahuddin (2014) states that the national education primary concepts are also applied to Islamic education. In the Islamic context, the curriculum embraces diverse subjects in accordance with the Islamic spirit to achieve systemic and dynamic educational goals. However, the rapid development of information today is undeniable. As such, Islamic education needs to adapt to this fastpaced information era. It requires a conceptualization and reorientation of Islamic education to impact teaching and learning substantially (Syukron, 2017). Waghid (2014) points out that to be sustainable in the modern context, the core of Islamic education should be reformulated to help solve various modern issues encountered by Muslims. Yet, reconceptualization or reformulation of Islamic education is not easy since it needs to maintain Islamic values while incorporating modern elements into its system (Rosyad, 2020). Integrating science, including other generic skills (communication skills, ICT skills, teamwork skills, and problem-solving skills) into the Islamic boarding school curriculum enables the students to improve their academic qualifications that eventually pave their future life terrains successfully.

The Implementation of Curriculum 2013
Curriculum 2013 or K13 (Kurrikulum 13) has been implemented since 2013/2014 based on the circular letter of the Ministry of Education and Culture of the Republic of Indonesia No. 156928/MKK.A/KR/2013. This curriculum concerns students' attitudes, knowledge, and skill competence. The curriculum also expects that students have a good manner and discipline. Thus, Curriculum 2013 is commonly known as the character-based curriculum.
Indonesian school curricula have undergone several changes throughout the years due to several factors, including teaching and learning needs and technological advancement (Hawanti, 2014;Shalihin et al., 2019;Silahuddin, 2014). Regarding curriculum 2013, Mulyasa (2013) mentions that this curriculum allows students to use their own knowledge to evaluate the right character values and display good behavior in everyday life. Curriculum 2013 focuses on three aspects of assessment: affective, cognitive, and psychomotor. In addition, the curriculum also emphasizes subject integration, character education, and thematic lessons (Michie, 2019). Hasan (2013) adds that the curriculum balances soft and hard skills with varied standards, including competence, content, process, and assessment. Specifically, Curriculum 2013 intends to motivate the teachers to improve their abilities in looking for new knowledge as much as possible. Nowadays, students have mastered the way to look for information by using modern technology. Yet, students should be encouraged to be more responsible and critical about their behaviors and become a more productive, creative, innovative, and effective generation.

English Subject Learning Materials Integration
In this global era, mastery of foreign languages is a must for Islamic boarding school students (Aulia et al., 2021). Muslim scientists are expected to master the contents of the Quran and apply them in social life. On the other hand, technological advancement has penetrated all human life aspects. As such, Islamic societies, including students studying at Islamic boarding schools, are expected to be able to utilize this technological development for the sake of Islamic community welfare.
It is understood that the amount of valuable information regarding science and technological development is available in various foreign languages, one of which is English. This requires students at Islamic boarding schools to learn English well. To this end, Islamic boarding schools, as the front-line educational institutions in developing Islamic education, should integrate their teaching and learning materials, especially English subject learning materials, into their curriculum (Wastyanti, 2019). English learning materials refer to all things that teachers and learners can utilize to facilitate learning. The learning materials could be videos, DVDs, emails, YouTube, dictionaries, books, photocopied exercises, newspapers, photographs, live talks, instructions, student tasks, and discussions between learners (Tomlinson, 2011). Islamic boarding schools that combine national and religious curricula can unite their teaching and learning materials by integrating the material in the guidebooks and syllabus with agreed religious materials. English teachers can adjust their teaching materials provided in the teacher handbook with related religious studies regarding the English subject materials. This adjustment, in addition, should be based on both core and basic competencies stipulated in the targeted lesson plans. Tomlinson (2011) adds that teaching materials include discussions, talks, debates, and other seminar activities. Therefore, in integrating English teaching materials, English teachers at Islamic boarding schools can use various extracurricular activities conducted at these schools, including Muhadharah (Islamic talks), debate, and other Islamic seminars by using English to strengthen students' English skills. Students at Islamic boarding schools should be habituated to reading English texts and critically analyzing issues written in such texts. It is also urged that the English teachers at Islamic boarding schools be more creative in choosing the teaching and learning materials to suit both Islamic teachings as part of the core focuses of the schools and general education as prescribed in the teachers' and students' handbooks.
The integration of English teaching and learning materials at Islamic boarding schools could be accomplished through a variety of teaching and learning strategies, such as peer discussions, role-plays, cooperative learning forums, and other events unique to Islamic boarding schools (Berkowitz & Bier, 2005). It is strongly advised that schools prepare various processes, including the planning, teaching, and learning stages, as well as the assessment stage, while integrating English learning resources supplied in English manual books (Budiarta et al., 2018). Teachers must understand the aim of the handbooks' mandatory contents and then incorporate their essences or substances into the contexts of Islamic boarding schools.

Research Design
This qualitative study focused on integrating English subject teaching and learning materials of Curriculum 2013 into the Islamic boarding school curriculum context at two Islamic boarding schools in Banda Aceh, Indonesia. As a qualitative study, this study sought to explore and understand the information from individuals and groups that describes social and human problems (Creswell, 2014). We believed that this qualitative study could give us a deep insight into the views of the Islamic boarding school teachers and leaders. For this reason, we employed a case study approach to explore these stakeholders' responses to figure out appropriate ways of integrating English subject materials in the Curriculum 2013 comprehensively into the Islamic boarding school curriculum. We used a case study approach as we believed that this approach could generate a certain complex issue in a real context (Yin, 2018).

Participants
This study took place at two Islamic boarding schools in Banda Aceh, Indonesia. Eleven participants participated in the study, consisting of two Islamic boarding school principals and nine English teachers teaching at these two Islamic boarding schools. We purposively selected those participants based on their roles at the schools and their teaching experiences. We only selected the English teachers whose teaching experience was more than ten years, expecting that they have had adequate experience in implementing Curriculum 2013, both its original and revised version.
To carry out this research, we obtained permission from the schools. We received an approval letter to conduct this study after providing the required documents and filling out the research permit application. In addition, we also provided the consent forms for the participants who were interested in taking part in this study. Their names are kept confidential and anonymous in reporting the data to keep all participants' safety and privacy.

Data Collection
The primary data for this study came from interviews. We developed the interview questions regarding integrating English subject teaching and learning materials of Curriculum 2013 into the Islamic boarding school curriculum context for the study purposes. We conducted the interviews in Bahasa Indonesia (Indonesian language) following the participants' preferences. All interview transcripts were later translated into English, and all presented quotes in this study are based on the translation of the interviews.
We employed semi-structured interviews to explore more information that fit the research questions proposed in this study. The interviews took approximately 30 to 60 minutes for each participant. We carried out face-to-face and one-on-one interviews to ensure that the interviewees could properly express their ideas (Creswell & Creswell, 2018). We did not employ a specific framework when interviewing our participants. To put our participants at ease and prepare them to answer our main questions about the integration of the English material, we first have a few minutes of discussion about their teaching experiences at Islamic boarding schools. We began exploring the problems of incorporating English materials from the Curriculum 2013 into Islamic boarding schools in greater depth once our participants felt confident and comfortable doing so.

Data Analysis
The interview results were fully transcribed to obtain information related to the research questions, and then open coding was used to code the transcribed data (Corbin & Strauss, 2015). We carefully selected, simplified, and abstracted more appropriate information during the transcribing process. After coding the data, we identified common emerging themes from all interview results into categories (Corbin & Strauss, 2015;Richards, 2009). Finally, we reported the findings based on the themes that emerge from the interview process.

RESULTS AND DISCUSSIONS
This study explores important information regarding integrating English subject teaching and learning materials of Curriculum 2013 into the Islamic boarding school curriculum context. By interviewing the Islamic boarding school principals and English teachers, we hope to gain valuable insights related to effective ways to better reform curriculum integration. These interview results are reported under specific themes.

Teachers' Views on Integrated Curriculum
The findings indicate that all participants of this research have the same opinion on the integrated curriculum. They agree that curriculum integration has brought significant changes in managing teaching and learning material. The participants need to integrate their general knowledge into Islamic understanding to meet the Islamic boarding school curriculum objectives. This curriculum integration, in the end, can enhance both teachers' and students' general and Islamic knowledge. The teachers believe that the curriculum integration provides good opportunities for students to enhance their general knowledge and Islamic-related knowledge. This is summarized in the following excerpt: (1) The integrated curriculum is not a new product for us here at the boarding school. We have practiced our teaching by integrating the national curriculum and the Islamic boarding school curriculum. In the beginning, we see that there are some approaches that we need to change, including how to adjust the materials that we use to meet the curriculum K13. But when we are familiar with it, it is not difficult to do it. We believe that this curriculum integration is a good way to improve our general and Islamic knowledge. This curriculum integration is good not only for us as teachers but also for students. Before we teach our students with particular materials provided in the textbook, we need to enrich our Islamic understanding of related issues that we can use to teach our students. At this point, students can study two important fields of knowledge. While they are learning English, they also learn Islamic teachings. In the end, we here at boarding school equip our students with general and Islamic knowledge. (P3, 8, 9) The usefulness of curriculum integration has also been acknowledged by another participant, saying that students studying at boarding schools have a twofold advantage: they have an excellent opportunity to study general knowledge, including science, humanities, languages, and Islamic-related teachings. This finding corroborates Hudson's (2012b) and Beane's (2016) research findings, revealing that curriculum integration enhances the understandings and abilities of the students in different learning areas at the same time. This knowledge integration will produce qualified Indonesian future generations, namely those who have good skills in the sciences along with noble characters.
(2) Integrating Curriculum 2013 into the Islamic boarding school curriculum enables students to expand their general and religious education simultaneously. Students have a great opportunity to study general study fields like foreign languages and sciences, while at the same time they learn about their religious teachings. Students also recite Al-Quran and interpret and understand its meaning in the nighttime. As a result, this curriculum integration will strengthen students' general skills and enrich their religious values. In the future, we will have a generation that is good at general knowledge and good at religious understanding. (P1, 3) To support the quotation above, the other two participants (Islamic boarding school principals) also assert that integrating Curriculum 2013 into the Islamic boarding school curriculum can produce generations who master science and technology and become faithful individuals.
(3) We see that the integration of Curriculum 2013, including English lessons in the Islamic boarding school curriculum, is extraordinary. English is the world's language, and everyone must master it, including students studying in Islamic boarding schools. They will be the next generation of our nation. We must educate generations who master IPTEK (science and technology) and IMTAK (faith and piety). We are sure that these students will be our good future generations because they have sufficient general and Islamic knowledge. (P1,2) When asked specifically about integrating English subject teaching and learning materials into the Islamic boarding school curriculum, most teachers said that students studying at Islamic boarding schools mostly pursue their knowledge at numerous wellknown universities in Indonesia by choosing various favorable study fields, including sciences. The participants add that if the students studying at Islamic boarding schools can master English well, they will be able to comprehensively absorb and analyze information and knowledge written in English. This will provide additional values for our future generation, specifically those who have a good understanding of science, a noble personality in national life, a good moral character, and are moderate and tolerant.
(4) We are proud of students who graduated from Islamic boarding schools. Many of them continue their education at some well-known universities in Indonesia. In addition, by having good English skills, they can read and digest information published in English. Besides mastering sufficient scientific knowledge, they have good religious knowledge as well. We need more generations who have these knowledge combinations in the future. (P4,5,7) The excerpts in (4) indicate that the integration of Curriculum 2013 into the Islamic boarding school curriculum positively impacts students' educational development. Teachers believe that this curriculum integration allows students to focus on their general knowledge. However, at the same time, they also have a chance to study more about Islamic teaching values, including interpreting the meaning of the Quran that they recite. When both general education and religious education unite, this may enable students to be ethical and have good moral character (Mustapha et al., 2016).

Integrating English Materials
The findings regarding integrating English teaching and learning materials available in Curriculum 2013 into the Islamic boarding school curriculum reveal two themes: approaches to integrating curriculum and English materials integration.

Approaches to integrating curriculum
The participants state that there should be a clear regulation and willingness from every stakeholder involved in this curriculum integration intention to successfully integrate Curriculum 2013 into the Islamic boarding school curriculum. They mention Habiburrahim, Muhammad, L.  that every regulation and policy will run effectively if all concerned entities have the same vision in viewing the goals that have been formulated.
(5) In order to integrate the curriculum, there should be clear rules from the school so that there are clear guidelines for us (teachers) who will implement it in the field. We also think this clear regulation and policy can be part of legal standing, giving us the same perception about such regulations and ways of implementing teaching and learning programs. Our school has some regulations that integrate teaching materials to suit the Islamic boarding school curriculum. (P3, 8, 9) In addition, the participants agree that Islamic boarding schools should have a clear regulation or policy on guidelines for providing the teaching and learning process, as well as what forms of Islamic-related teaching materials are permitted and prohibited. Teachers, for example, are still unsure about providing sex education and reproductive health information, which are still considered taboo in Islamic boarding schools. They also believe that the regulation enables them to have the same understanding of the curriculum integration objective and the materials that suit Islamic boarding schools' teaching and learning values. The English teachers assert that the Islamic boarding schools should provide their own materials regarding the book the teachers and the students have. This is critical to have the same standardized English materials teachers use in teaching English subjects at Islamic boarding schools. They said that teachers could not simply use the material based solely on their interest because they need to select the materials related to the prescribed materials in the English handbook for the students to succeed in the exit examination test (Ujian Akhir Nasional or the National Final Exam). The substitute materials related to Islamic teachings and values that teachers might use should be stated clearly in the Islamic boarding school curriculum and syllabus. We noticed that the English teachers used the English book issued by the ministry of education during the interviews.
Besides the law that governs this curriculum integration, another participant says that the teachers teaching at Islamic boarding schools should have the same perception of the objective of curriculum integration at Islamic boarding schools. The participant adds that the main mission of the Islamic boarding school is to provide students with science and religious knowledge. These two cores are the focus of our school, which makes Islamic boarding schools differ from non-boarding schools. He ends his conversation with a meaningful message: (7) Islamic boarding schools nurture students' minds and enrich their souls. (P1) After providing some information on regulations that can strengthen the intention of integrating the curriculum, the participants share their understanding of integrating English subject materials into the Islamic boarding school curriculum. This teaching and learning material integration is reported under the 'English material integration' theme.

English materials integration
The integration of English subject materials in Curriculum 2013 into the Islamic boarding school curriculum is by adjusting the teaching and learning materials available in the handbook used by teachers and students for the English subject. Yet, the participants say that they cannot integrate all the English materials provided in the textbook. They usually integrate texts with the same format, for instance, narrative texts. The participants added additional text related to a story about Islamic teachings in the narrative texts. This is reported by a participant as follows: (8) The implementation of curriculum integration at our school does not apply to all materials; it depends on the discussion topic. For example, in a narrative text, we use additional text that resembles the narrative text provided in the textbook, as an Islamic text regarding the fasting concept in Islam. We use this text because we think that while learning about a narrative text, students also get information about fasting and its benefit. This kind of material exchange and integration will assist students to learn a narrative text and increase their religious understanding of the essence of fasting. (P9) Another participant also claims that it is easy to integrate the English subject materials in Curriculum 2013 into the Islamic boarding school curriculum by adjusting its texts. This teacher says that the most important thing for students in understanding the targeted skills (listening, speaking, and reading comprehension) that they need to master after learning a chapter in the English textbook. As long as the teachers teach the targeted skills prescribed in the textbook appropriately, they can use various materials to enlighten their students' English skills. This teacher says that: Another participant (P8) also agrees that the most common way of integrating English subject materials in Curriculum 2013 into Islamic boarding schools is to modify the English-related topics with other religious topics. This topic is always in line with the syllabus, but the participant chooses different materials related to the focus and skills specified in the syllabus. For instance, the participant adds that she modifies the content of English speech, part of an extracurricular activity at an Islamic boarding school. She asks her students to deliver an English speech in front of the class about the benefit of prayer from a health perspective.
(10) Oftentimes, I ask my students to deliver English speeches by choosing a topic related to Islamic teachings like prayer and its benefits from a health perspective. (P8) Like participant 8, participant 7 also said that she always adds some Islamic materials that relate to the texts provided in the book. subject materials into Islamic boarding school curriculum context: Insights from Aceh, Indonesia | 678 Integrating English materials into the Islamic boarding school curriculum can also be conducted through English listening-related topics. Incorporating listening skills with related topics and materials has been explored in some research (e.g., Berke, 2000;Hudson, 2012a;Tavil, 2010). In addition, McPhail (2018, p. 6) says that "… bringing two subjects together, students might be 'hooked-in' to subjects they were less interested in". In the Islamic boarding school context, teachers can use various religious speeches or Da'wah/Ceramah recordings which Muslim preachers deliver in English. Again, this approach assists students in developing their listening skills and enhances their Islamic understanding. Participant 11 reported that "In the listening practice of unit 1 activity 7 of the Bright handbook, instead of listening to "Look at the speaker" song, I ask my students to listen to Abu Ammaar Yasir Qadhi's lecture. Abu Ammaar is one of the well-known preachers in Islam". This participant adds that "… listening to Islamic lectures will give students two benefits: knowledge about listening skills and knowledge about Islam". Again, these materials substitutions should always meet the syllabus contents and standards, including learning objectives, level of material difficulties, and assessment procedures (Manan et al., 2020).
The participants also acknowledge that the English subject teaching and learning materials integration at Islamic boarding schools can be implemented by adding extracurricular programs at a certain time. For instance, a teacher can use the Muhadharah program (an extra class for English and Arabic speaking programs) to link the materials prescribed in the syllabus with Islamic content knowledge.
Participant 11 said that: The effectiveness of this curriculum integration to improve students' particular skills and knowledge is evident. Hinde (2005) and Hudson (2012b) assert that curriculum integration involving the materials and skills in diverse subjects may help better students' learning experiences.

Challenges of Integrating English Subject Materials
The results of integrating English subject teaching and learning materials into the Islamic boarding school curriculum context are reported under two themes: lack of teachers' competence in Islamic teaching knowledge and subject overload.

Teachers' lack of Islamic teachings knowledge
The majority of respondents say there are many challenges in integrating English subject teaching and learning materials of Curriculum 2013 into the Islamic boarding school curriculum. The teachers sometimes do not have a good understanding of the Islamic teaching topics that they can integrate with the topic prescribed in the textbook. They sometimes have to study more to find the right information about issues of Islamic teachings that they want to integrate into the topic prescribed in the syllabus. Besides, the selected materials should align with the materials determined in Curriculum 2013. This is reported by participants 6 and 10 as follows: 679 | Studies in English Language and Education, 9(2), 667-684, 2022 (13) Sometimes we face many difficulties and problems in integrating the teaching and learning materials at school. First of all, we have to understand the topic that we will teach to our students, and then we have to find another teaching resource that is compatible with the materials specified in the syllabus. We cannot just simply find the Islamic teaching texts or audios. We need to analyze if the materials meet the Curriculum 2013 requirements and the students' ability to understand such materials. (P6, 10) The lack of teachers' knowledge of Islamic related teachings is also admitted by participant 8, saying that: In any case, the inadequacy of Islamic-related knowledge can hamper a teacher in selecting teaching and learning materials that suit the topic listed in the syllabus. Teachers can be reluctant to choose appropriate Islamic materials that link to the syllabus of Curriculum 2013 because they worry that they cannot master the issues of Islamic knowledge well. This can be problematic if the students ask questions relating to the materials which are being discussed. Participants 3, 7, 9, and 11 reported: (15) We are not brave enough to carelessly choose Islamic materials if we do not understand their content. We are afraid of being unable to answer students' questions correctly when they ask questions regarding the issues we are discussing. (P3, 7, 9, 11) The excerpt in (15) indicates a close relationship between teachers' understanding of Islamic knowledge and their ability to variously select Islamic texts and movies or videos that they can use as the substitute or additional materials that meet the syllabus requirement. With this regard, Hinde (2005, p. 108) states that "… when teachers are knowledgeable about content areas and integrate them effectively, students' achievement increases". Teachers' inability to select the teaching and learning materials leads them to focus merely on the materials found in the textbook. To this end, curriculum integration cannot be performed appropriately.

Subject overload
Subject overload is also one of the most common themes that emerge during the interview process. Teachers claim that students studying at Islamic boarding schools have to study extra hours and subjects. In the morning time, students need to learn all subjects prescribed in Curriculum 2013. They also have to study more subjects relating to Islamic teachings and knowledge in the evening and nighttime. English is one of the subjects of this curriculum 2013. It means that in the morning time, students must study English to fulfill the national curriculum requirement. In the evening time, in addition, students should also join an English program and other Islamic-related studies to meet the Islamic boarding school curriculum targets. This condition takes both students' and teachers' time; they need to prepare themselves to study in the morning and the evening. According to teachers, such overloading may negatively affect both students and teachers, especially in arranging an appropriate time for a certain subject. This grievance is expressed by some teachers as extracted in the following quotation: Habiburrahim, Muhammad, L. Auni, Hafidhah & I. K. Trisnawati, Integrating English subject materials into Islamic boarding school curriculum context: Insights from Aceh, Indonesia | 680 (16) The problem here is that there are so many subjects that students need to study, while the allocated time for learning is limited. On the one hand, we have to ensure that all materials prescribed in the syllabus should be taught completely, while on the other hand, we need to teach other Islamicrelated subjects. Sometimes we cannot finish even a chapter within an allocated time. It is difficult for us and students to understand much information simultaneously. (P4, 5, 6, 8, 10) Subject overload and limited study time are also the driving factors that prevent the maximal performance of curriculum integration (Rodriguez, 2020). Research by Chester et al. (2013) concludes that curriculum integration emerges various impacts on teachers' work, including excessive workloads faced by both teachers and students. In various countries, curriculum or subject overload has been reported in some research (e.g., Dare et al., 1997; National Council for Curriculum and Assessment [NCCA], 2010; Rennie et al., 2011;Sethi & Khan, 2020;Vinson, 2001). Teachers assert that learning for long hours makes students tired and unable to focus. The teachers would instead focus on the materials described in the syllabus than using other Islamic-related resources.
(17) Sometimes we cannot bear to see children too tired from studying. They have a long study time; they study in the morning, evening, and in the night time as well. They also have so much homework to work with. Often, some students are sleepy due to fatigue. So, sometimes we prioritize the material listed in the syllabus and Curriculum 2013 so that the students will pass the UAN. (P7, 8, 10, 11) Long hours of study and subject overload are other main issues in curriculum integration. Often, teachers must focus on teaching materials that have been written in the syllabus because the final target of teaching and learning is that students must be able to pass the exit examination test. When this becomes the main target, teachers will no doubt work all out to focus on the teaching and learning materials that have been assigned rather than take a risk by selecting materials that are not listed in the curriculum or the syllabus.

CONCLUSION
The current study unveils some important facts in exploring teachers' perception towards integrating English subject teaching and learning materials of Curriculum 2013 into the Islamic boarding school curriculum context. This study highlights that integrating English subject teaching and learning materials into the Islamic boarding school curriculum significantly enhances students' general knowledge, including English language skills and Islamic knowledge. This knowledge integration may, in addition, produce quality generations: generations who have a strong background in science and technology and generations who have good religious knowledge and strong morals and spirituality.
In integrating the English teaching and learning materials into the Islamic boarding school curriculum, the participants recommend that there should be clear guidelines or regulations that support this curriculum integration process. Aside from clear guidelines, the participants also suggest that the teachers at Islamic boarding schools should have the same vision, ensuring that curriculum integration can be implemented successfully.
Regarding integrating English subject teaching and learning materials into the Islamic boarding school curriculum, this research suggests that adjusting the prescribed materials or texts available in the Curriculum 2013 with the texts related to Islamic teachings is the most common approach that the teachers employ. This unveils that teachers need to comprehensively understand the information and knowledge provided in the texts to link it meaningfully with the Islamic teaching resources.
Teachers' inadequacy of Islamic-related knowledge and the subject overload that students have to study are the two most common challenges teachers face in integrating English materials into the Islamic boarding school curriculum. Teachers acknowledge that sometimes they are not brave enough to substitute the listed materials with Islamic-related materials because they do not have a good understanding of the information and knowledge provided in the substituted resources. In this regard, teachers tend to focus more on the materials suggested in the syllabus of Curriculum 2013 rather than taking a risk by adding more additional materials taken from Islamic learning resources. Subject overload is also part of the teachers' concern in integrating these two curricula. Teachers argue that students at Islamic boarding schools have to study more subjects. This can be problematic for teachers and students in managing their learning time.
This study provides information for teachers, schools, and government authorities in overseeing curriculum integration that is not easy to deal with. Even though the number of participants involved in this study is relatively small and does not involve other relevant stakeholders, the findings provide important information on curriculum integration issues from the perspectives of teachers and school leaders. The limitation of this study can function as an important consideration for further researchers to involve not only teachers but also students and other government authorities. The involvement aims to seek their opinions regarding the best practice of integrating English subject teaching and learning materials into the Islamic boarding school curriculum.