The particular dialect or language that a person chooses to use on any occasion is called a code 2859 Copyright © 2024 The Author IDEAS is licensed under CC-BY-SA 4.0 License Issued by English study program of IAIN Palopo IDEAS Journal of Language Teaching and Learning, Linguistics and Literature ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) Volume 12, Number 2, December 2024 pp. 2859 - 2869 Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching Rahmawati Upa1, Sri Damayanti2, Hafirah Patang3, Paldy4, Miltan5 E-mail: rahmawatiupa22@gmail.com1, yanthie_uncok@ymail.com2, hafirahpatang@gmail.com3, paldy@uncp.ac.id4 miltanpomandia@gmail.com5 1PPG FKIP, Universitas Cokroaminoto Palopo, Sulawesi Selatan 2,3Pendidikan Bahasa Inggris, Universitas Cokroaminoto Palopo, Sulawesi Selatan 4PPG FKIP, Universitas Cokroaminoto Palopo, Sulawesi Selatan 5SMP Negeri 11 Palopo, Sulawesi Selatan Received: 2024-10-26 Accepted:2025-02-08 DOI: 10.2456/ideas. v12i2.5749 Abstract This research examines the use of lesson study as a method for enhancing differentiated instruction in English language teaching. A qualitative case study approach was employed at SMK Negeri 1 Palopo, involving 12 English teachers, 4 lecturers, and students. The aim of the study was to explore how lesson study could improve differentiated instruction through collaborative planning, observation, and reflection. The study was carried out over two teaching cycles: the first cycle focused on process differentiation by allowing students to choose their preferred learning media, while the second cycle refined this approach by using homogeneous grouping and creating differentiated worksheets according to students' abilities. The findings indicated that the first cycle’s process differentiation posed challenges, particularly for lower-ability students, as heterogeneous grouping led to passive involvement. On the other hand, the second cycle, which involved providing targeted support through homogeneous grouping and personalized worksheets, led to notable improvements in student engagement and understanding, especially among lower-ability students. This research demonstrates the effectiveness of lesson study in refining differentiated instruction strategies and offers a structured framework for teachers to adjust their methods based on real classroom experiences. The findings provide valuable insights for educators aiming to develop inclusive learning environments that cater to the diverse needs of students http://u.lipi.go.id/1457703302 mailto:rahmawatiupa22@gmail.com mailto:yanthie_uncok@ymail.com2 mailto:hafirahpatang@gmail.com mailto:paldy@uncp.ac.id Rahmawati Upa, Sri Damayanti, Hafirah Patang, Paldy, Miltan Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching 2860 Keywords: Differentiated Instruction, Lesson Study, English Language Teaching, Student Engagement, Teacher Collaboration Introduction Differentiated instruction is a teaching method that adapts content, process, and products to meet the diverse needs, abilities, and interests of students. In English language teaching, where students often have varying levels of language proficiency, learning styles, and cultural backgrounds, this approach is particularly important. In Indonesia, where English is taught as a foreign language, teachers face significant challenges in addressing the wide range of student needs within large classrooms. According to research by the Indonesian Ministry of Education (2022), over 70% of English teachers in Indonesia report difficulties in accommodating the different language proficiency levels of their students, a challenge compounded by limited resources and a lack of professional development opportunities. Despite the growing emphasis on differentiated instruction, many teachers find it difficult to implement effectively. To overcome these obstacles, teachers need advanced pedagogical skills, continuous professional development, and adequate resources to adapt their teaching strategies. One promising solution is lesson study, a collaborative professional development approach that originated in Japan. Through lesson study, teachers collaborate to plan, observe, and analyze lessons, focusing on student learning and instructional strategies. This cyclical and reflective process promotes ongoing improvement and allows teachers to adjust their methods based on actual classroom experiences and evidence. Research has shown that lesson study has positive effects on teacher collaboration, instructional quality, and student outcomes (Suardi, R. Upa, & R. Pilu, 2021; H. Patang, H. Machmoed, & Nasmilah, 2020). Recent studies suggest that combining lesson study with differentiated instruction can greatly enhance teaching practices in diverse classrooms, making learning more personalized and inclusive. Specifically, lesson study provides a structured framework for teachers to explore and experiment with different differentiation techniques in real classroom environments. However, research on how lesson study can specifically optimize differentiated instruction in English language classrooms is still limited. While differentiated instruction is widely recognized as essential in English language teaching, there is a need for more research into how collaborative professional development models like lesson study can help teachers refine and implement effective differentiation strategies. This study aims to address this gap by examining how lesson study can support differentiated instruction in English language classrooms, particularly in the context of Indonesia. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2861 This study was conducted in the city of Palopo, South Sulawesi, Indonesia, at SMK Negeri 1 Palopo, a vocational high school. English language teaching at this institution faces several challenges, including large class sizes, students with varying levels of English proficiency, and limited access to digital learning resources. According to the Indonesian Ministry of Education (2022), the average English proficiency of high school students in Palopo falls below the national standard, highlighting the need for more effective teaching methods to meet students’ diverse needs. In this setting, differentiated instruction is critical to address the varying levels of language proficiency, with some students struggling to comprehend basic language concepts while others are ready for more advanced material. By adopting lesson study, teachers have an opportunity to collaborate and reflect on their teaching practices, ultimately fostering a more inclusive and personalized learning environment. Combining lesson study with differentiated instruction offers a powerful strategy for addressing the challenges of diverse classrooms. Lesson study encourages collaborative, reflective practice, allowing teachers to fine-tune their differentiation techniques based on real-time feedback from colleagues and students. This collaboration enables teachers to share best practices, experiment with different differentiation strategies, and refine their methods to better meet the needs of all students. In English language teaching, where differentiation can be particularly difficult due to students’ varied levels of proficiency, lesson study provides a supportive structure for teachers to explore and implement differentiation strategies that are responsive to these differences. The reflective nature of lesson study also ensures that teachers can continuously assess and adjust their approaches, resulting in more effective instruction that promotes greater student engagement and achievement. Based on the background then the objectives of this study is to investigate how lesson study can support differentiated instruction in English language classrooms. The findings from this study are expected to contribute to the growing body of research on the integration of lesson study and differentiated instruction, providing valuable insights for educators, policymakers, and professional development programs in Indonesia and other similar educational contexts. By promoting a more personalized and inclusive learning environment, this approach has the potential to significantly improve the quality of English language teaching and learning. Rahmawati Upa, Sri Damayanti, Hafirah Patang, Paldy, Miltan Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching 2862 Literature Review 1. Differentiated Instruction Differentiated instruction is a teaching approach that involves tailoring instruction to meet the varied needs, interests, and abilities of students. According to Tomlinson (2001), differentiated instruction involves modifying content, process, and product based on students' readiness levels, interests, and learning profiles. This approach is especially relevant in English language teaching, where students often have diverse language proficiencies and learning needs. Recent studies emphasize the role of technology and data-driven methods in supporting differentiated instruction, highlighting its effectiveness in promoting student engagement and achievement (Santangelo & Tomlinson, 2022). 2. Lesson Study Lesson study is a collaborative professional development practice that originated in Japan. In this model, teachers work together to plan, observe, and analyze lessons with the aim of improving instructional practices. According to Lewis, Perry, and Murata (2019), lesson study fosters deep reflection on teaching and learning, enabling educators to develop more effective and student-centered teaching strategies. This model has been widely adopted in various educational contexts and has been shown to enhance teacher collaboration and instructional quality (Huang & Shimizu, 2021). 3. Integrating Lesson Study and Differentiated Instruction The integration of lesson study with differentiated instruction presents a promising approach to addressing the diverse needs of students in English language classrooms. Warwick, Vrikki, Vermunt, and Mercer (2019) found that lesson study facilitates the exploration and implementation of differentiated instruction strategies by providing a structured framework for teachers to collaboratively plan and reflect on their teaching practices. Through lesson study, teachers can experiment with different differentiation techniques, gather feedback from peers, and make data-driven adjustments to their instructional methods. 4. Application in English Language Teaching Research specific to the application of lesson study in English language teaching suggests significant benefits. Takahashi and McDougal (2019) demonstrated that lesson study helps teachers develop and refine instructional strategies that are responsive to the varying linguistic and cultural backgrounds of students. By engaging in lesson study, English language teachers can better address individual student needs, leading to improved language acquisition and academic performance. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2863 5. Challenges and Considerations Despite the potential benefits, there are challenges associated with the implementation of lesson study and differentiated instruction. Teachers may face difficulties in coordinating schedules, accessing necessary resources, and maintaining ongoing commitment to the collaborative process. Additionally, there may be resistance to change from educators who are accustomed to traditional teaching methods (Chappell, Craft, Burnard, & Cremin, 2021). Addressing these challenges requires administrative support, professional development opportunities, and a school culture that values continuous improvement and collaboration. Method This study utilized a qualitative case study approach to investigate how lesson study can support differentiated instruction in English language classrooms. The research was carried out over two cycles of lesson study at SMK Negeri 1 Palopo in South Sulawesi, Indonesia, involving 12 English teachers, 4 English lecturers, and students. Participants were selected intentionally based on their experience with differentiated instruction and their involvement in the lesson study process. The participants included 12 English teachers from SMK Negeri 1 Palopo, 4 English lecturers from the Universitas Cokroaminoto Palopo, and students who participated in the lesson study cycles. Teachers were chosen for their previous experience with differentiated instruction and their willingness to collaborate in the lesson study process. The lecturers played a guiding role, offering expertise in pedagogical strategies, while students were selected based on their active participation in the English language classes. Multiple instruments were used for data collection to ensure a comprehensive understanding of the lesson study process and its effect on differentiated instruction: 1) Lesson Plans and Teaching Materials: These documents were examined to assess the alignment of differentiated instruction strategies with lesson content. The lesson plans were developed collaboratively during the planning phase of each cycle. 2) Classroom Observations: Observational data were gathered through field notes and video recordings during each lesson cycle. Observers focused on how teachers implemented differentiated instruction, interactions between teachers and students, and student engagement levels. Video recordings allowed for in-depth analysis of student-teacher interactions and group dynamics. 3) Reflection Notes: After each cycle, participants (teachers, lecturers, and researchers) engaged in reflective discussions and recorded insights regarding Rahmawati Upa, Sri Damayanti, Hafirah Patang, Paldy, Miltan Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching 2864 the implementation of differentiation strategies, challenges faced, and suggestions for improvement. Data were analyzed using thematic analysis to identify recurring themes and patterns related to the implementation of differentiated instruction via lesson study. The analysis followed these steps: 1) Transcription: All reflections and observational notes were transcribed verbatim for accuracy. Video recordings were also transcribed to capture both verbal and non-verbal classroom interactions. 2) Coding: The transcribed data were systematically coded to identify key themes related to differentiated instruction and lesson study. Open coding was first used to capture all relevant data, followed by axial coding to refine these themes. 3) Thematic Categorization: Identified themes were grouped into categories such as "teacher collaboration," "differentiation strategies," "student engagement," and "challenges in implementation." This helped to understand how lesson study influenced teachers' ability to implement differentiated instruction and its impact on students. 4) Data Triangulation: To enhance validity and reliability, triangulation was employed by comparing data from various sources. This cross-referencing strengthened the consistency and robustness of the findings. To ensure the study’s validity and reliability, several measures were implemented: 1) Triangulation: Data from multiple sources (observations and reflections) were cross-checked to ensure consistency and depth in the findings. 2)Member Checking: Teachers and lecturers reviewed the preliminary interpretations of the data during reflection sessions to verify the accuracy of the findings. 3)Peer Review: A peer researcher reviewed the analysis and findings to provide feedback and ensure that the conclusions were supported by the data. The two lesson study cycles were conducted over a period of four months. Each cycle followed these stages: 1) Planning: Teachers and researchers worked together to design lesson plans that incorporated differentiated instruction strategies. This planning stage lasted one week before each cycle. 2) Implementation: The lesson was taught by one teacher (the model teacher), with other teachers observing. This stage lasted one week per cycle. 3) Observation: During lesson delivery, researchers and teachers observed and took detailed notes on the effectiveness of the differentiation strategies used. 4) Reflection: After each lesson, a reflection meeting was held to discuss the strengths and challenges of the lesson. Adjustments to the differentiation strategies were made based on these discussions. Reflection occurred within one week after each cycle’s implementation. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2865 Results The research titled "Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching" was conducted over two teaching cycles. The purpose was to explore how the lesson study approach could optimize differentiated instruction for English language learners. Teaching was conducted over two cycles to evaluate the effectiveness of lesson study in enhancing differentiated instruction. The first cycle utilized process differentiation by allowing students to choose their preferred learning media, while the second cycle refined the differentiation strategy through homogeneous grouping and tailored worksheets. Lower-ability students also received additional teacher assistance. Each cycle involved planning, observing, and reflecting on the instructional strategies used. In the first plan, the researcher with the teaching team firstly identified the learning theme to focus on, which was "Simple past tense." This theme was chosen as an introductory content for entering the fantasy material, besides that according to the teacher, the students have not yet understood that material. After that, it was continued to discuss the lesson plan. It was planned that the class began by showing the students interactive multimedia about simple past tense and identifying past verbs in the text in groups. Process differentiation was implemented by allowing students to choose the learning medium (text, video, or audio) that best suited their preferences. Heterogeneous groups were formed, with each group containing students of varying skill levels. Once the identification process was complete, each group presented their findings to the class, explaining the past verbs they discovered and providing relevant example sentences. Next, students completed a worksheet independently that contained exercises related to the use of past verbs, allowing them to apply the understanding they had gained in a broader context. The differentiated instruction used was process differentiation, where students were given the freedom to choose the materials they would analyze, such as text, video, and audio. Finally, as part of the evaluation, students took a true-false quiz containing statements related to the use of past verbs, aiming to assess their comprehension of the material that had been taught. After planning, one of the teachers applied the lesson plan in the classroom while the others as observers including the researchers and then continued to reflection. In the reflection process, the observer found that dealing with the media choices and engagement, most students inclined toward text and video and none of them chose audio as it required more ability to listen and understand what they listened. The heterogeneous grouping led to an imbalance in participation. Students with higher abilities often took on leadership roles, leaving some lower- ability students as passive participants, dependent on their peers for guidance. Rahmawati Upa, Sri Damayanti, Hafirah Patang, Paldy, Miltan Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching 2866 This cycle revealed the need for more structured support, particularly for students in the basic group who were less confident in selecting and working with materials. So, the observer recommended forming homogeneous groups and ensuring that groups with basic abilities receive more support by the lecturer than other groups (process differentiation). The students’ worksheet (LKPD) is divided into three ability levels: basic, developing, and advanced. The basic group identifies past verbs, the intermediate group identifies nominal sentences in the past tense, while the advanced group identifies verbal sentences in the past tense, after identifying, they presented their works. After presentation, to measure their ability, they were given quiz. Besides that, it was also found by the observer that the multimedia used did not help students understand the material, so most students still had difficulty comprehending it. Additionally, the observer’s suggestion for the next lesson is to improve the interactive multimedia used by adopting more engaging multimedia for students. Based on the reflection, teachers including model teacher and the researchers redesigned the lesson plan to be practiced in the second cycle. In this cycle the differentiated instruction used was process differentiation. Process Differentiation through homogeneous grouping and tailored worksheets. Homogeneous groups were formed based on students' ability levels, and differentiated worksheets were created to align with each group’s capabilities. Additionally, the teacher provided increased assistance to the basic group to better support their learning. The students were divided into six group, each student category was divided into two groups (two groups for basic, intermediate, and advanced). The basic group’s worksheet focused on identifying past verbs, the intermediate group on identifying nominal sentences in the past tense, and the advanced group on analyzing verbal complex sentences. After the open class, in the reflection most of the observers found that one of the basic groups showed improved comprehension and engagement due to the additional support and simplified worksheet content. They actively participated and demonstrated a better understanding of past tense verbs while the other one kept in active. Intermediate and Advanced Groups with materials aligned to their ability levels, these groups worked independently and effectively. Intermediate students identified nominal sentences accurately, while the advanced group successfully tackled more complex verbal structures. Many students who were passive in cycle 1 became more engaged in cycle 2, benefiting from the tailored tasks and additional guidance provided. In particular, the basic group showed greater independence and participation. A Quizizz quiz was used to encourage active participation, with most students answering correctly and enthusiastically engaging with the activity. IDEAS, Vol. 12, No. 2, December 2024 ISSN 2338-4778 (Print) ISSN 2548-4192 (Online) 2867 Discussion Based on the finding it can be said that the shift from choice-based media differentiation in cycle 1 to a more structured approach with homogeneous grouping and tailored worksheets in cycle 2 proved beneficial for enhancing engagement and comprehension. Homogeneous grouping allowed the teacher to provide targeted support, and differentiated worksheets ensured that each group could work at a suitable level, leading to more effective process differentiation. The improvement in lower-ability students’ engagement indicates that more structured, supportive differentiation strategies can be essential for fostering active learning, particularly in heterogeneous classrooms. The lesson study approach, with its reflective structure, enabled the teaching team to iteratively refine their differentiation methods and create an environment where each student could actively engage with the material. This study highlights that while process differentiation through choice can promote autonomy, structured and guided differentiation approaches can better support lower-ability learners. Consequently, the lesson study proves to be a powerful way for optimizing differentiated instruction, adapting teaching strategies based on ongoing observations and reflections to enhance learning outcomes across diverse student groups. Conclusion The study “Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching" demonstrated that lesson study is an effective approach for refining and improving differentiated instruction strategies. Over two cycles, the implementation of different process differentiation techniques revealed valuable insights. In the first cycle, the use of process differentiation through media choice allowed students autonomy in their learning but highlighted the challenges faced by lower-ability students. Heterogeneous grouping led to passive participation among weaker students, as they relied on their higher-ability peers, and the freedom to choose media did not fully address their learning needs. In the second cycle, process differentiation was enhanced by introducing homogeneous groups and worksheets tailored to students' abilities, alongside increased teacher assistance for the basic group. This more structured approach resulted in significant improvements in student engagement, particularly among lower-ability students who benefitted from focused support. The advanced and intermediate groups also thrived with tasks matched to their skill levels, demonstrating the success of ability-based differentiation. Rahmawati Upa, Sri Damayanti, Hafirah Patang, Paldy, Miltan Implementation of Lesson Study as a Strategy to Optimize Differentiated Instruction in English Language Teaching 2868 For future research it is recommended to conduct studies on how lesson study supports differentiated instruction for students with varying English proficiency levels. This could involve examining strategies that are particularly effective for beginner, intermediate, or advanced students. 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