<![CDATA[Chemistry learning requires meaningful learning experiences to enhance students' learning motivation, yet the implementation of practicums in schools remains limited by laboratory facilities and is not supported by practicum worksheets that facilitate project-based learning. This study aims to develop and measure the validity, practicality, and effectiveness of a practicum worksheet for determining the pH range of natural indicators within a Project Based Learning model to increase students' learning motivation. The study employed a Research and Development (R&D) method with the ADDIE model, involving 35 students and 1 chemistry teacher as research subjects. Validity data were obtained through expert validation sheets, practicality data through teacher and student response questionnaires, and effectiveness data through learning motivation questionnaires (pretest-posttest) and learning outcome tests. The findings show that the developed worksheet was rated highly valid and feasible for use based on validators' assessments, highly practical according to both teacher and student responses, and effective in increasing learning motivation particularly in fostering a conducive learning environment while also supporting students' mastery of the acid-base material. Thus, the practicum worksheet for determining the pH range of natural indicators within a Project Based Learning model can serve as an alternative teaching material to optimize chemistry practicums and enhance students' learning motivation. ABSTRAK Pembelajaran kimia memerlukan pengalaman belajar yang bermakna untuk meningkatkan motivasi belajar peserta didik, namun pelaksanaan praktikum di sekolah masih terbatas oleh sarana laboratorium dan belum didukung oleh LKPD praktikum yang memfasilitasi pembelajaran berbasis proyek. Penelitian ini bertujuan mengembangkan serta mengukur kevalidan, kepraktisan, dan keefektifan LKPD praktikum penentuan trayek pH indikator alami dalam model Project Based Learning untuk meningkatkan motivasi belajar peserta didik. Penelitian menggunakan metode Research and Development (R&D) dengan model ADDIE, melibatkan 35 peserta didik dan 1 guru kimia sebagai subjek penelitian. Data kevalidan diperoleh melalui lembar validasi ahli, data kepraktisan melalui angket respons guru dan peserta didik, serta data keefektifan melalui angket motivasi belajar (pretest-posttest) dan tes hasil belajar. Hasil penelitian menunjukkan bahwa LKPD praktikum yang dikembangkan dinyatakan sangat valid dan layak digunakan berdasarkan penilaian validator, sangat praktis menurut respons guru maupun peserta didik, serta efektif dalam meningkatkan motivasi belajar terutama pada aspek terciptanya lingkungan belajar yang kondusif, di samping mendorong ketuntasan hasil belajar peserta didik pada materi asam basa. Dengan demikian, LKPD praktikum penentuan trayek pH indikator alami dalam model Project Based Learning dapat digunakan sebagai alternatif bahan ajar untuk mengoptimalkan praktikum kimia sekaligus meningkatkan motivasi belajar peserta didik.]]>
