<![CDATA[This study aims to develop a thermochemistry Electronic Student Worksheet (E-LKM) based on Problem Based Learning (PBL) assisted by the wizer.me website and to determine the level of validity and practicality of the resulting product. This study is a Research and Development (R&D) study that refers to the Plomp development model, including the preliminary research and prototyping phase up to prototype IV. The research subjects consisted of five chemistry lecturers as validators, two teachers and twelve students of grade XI Phase F of SMA Pertiwi 1 Padang. The research instruments were validity sheets and practicality questionnaires. Data were analyzed qualitatively and quantitatively using the Aiken's V index for validity and the practicality percentage for practicality. The results showed that the PBL-based thermochemistry E-LKM had a high level of validity with an average Aiken's V value of 0.88 (valid category). The practicality test showed a percentage of 92.96% based on teacher responses and 91.17% based on student responses, both of which are categorized as very practical. Thus, the PBL-based thermochemistry e-LKM supported by the wizer.me website is declared valid and practical, and is suitable for use as a digital teaching material to support chemistry learning and develop critical thinking skills in high school students. ABSTRAK Penelitian ini bertujuan untuk mengembangkan Lembar Kerja Murid Elektronik (E-LKM) termokimia berbasis Problem Based Learning (PBL) berbantuan website wizer.me serta mengetahui tingkat validitas dan praktikalitas produk yang dihasilkan. Penelitian ini adalah penelitian Research and Development (R&D) yang mengacu pada model pengembangan Plomp, meliputi tahap penelitian awal dan tahap pengembangan hingga prototipe IV. Subjek penelitian terdiri atas lima dosen kimia sebagai validator, dua guru dan dua belas murid kelas XI Fase F SMA Pertiwi 1 Padang sebagai subjek uji kepraktisan. Instrumen penelitian berupa lembar validitas dan angket praktikalitas. Data dianalisis secara kualitatif dan kuantitatif menggunakan indeks Aiken’s V untuk validitas dan persentase kepraktisan untuk praktikalitas. Hasil penelitian menunjukkan bahwa E-LKM termokimia berbasis PBL memiliki tingkat validitas yang tinggi dengan nilai rata-rata Aiken’s V sebesar 0,88 (kategori valid). Uji kepraktisan menunjukkan persentase sebesar 92,96% berdasarkan respon guru dan 91,17% berdasarkan respon murid, keduanya termasuk kategori sangat praktis. Dengan demikian, E-LKM termokimia berbasis PBL berbantuan website wizer.me dinyatakan valid dan praktis serta layak digunakan sebagai media pembelajaran digital untuk mendukung pembelajaran kimia dan pengembangan kemampuan berpikir kritis murid SMA/MA. ]]>
