<![CDATA[This study was conducted based on initial observations of mathematics learning among fifth-grade students at SD Negeri 1 Jatianom. The observations indicated that students’ mathematics learning outcomes were still not optimal, particularly in addition of fractions, and the use of concrete learning media had not been optimally implemented. Therefore, this study aimed to determine the effectiveness of plastic waste-based teaching aids in improving students’ mathematics learning outcomes. This study employed a mixed-method approach with a one-group pretest-posttest design for quantitative data and classroom observations for qualitative data. The participants were 20 fifth-grade students selected using total sampling. Data were collected through learning outcome tests and observations of students’ activities during the implementation of plastic waste-based teaching aids. Quantitative data were analyzed by comparing pretest and posttest scores and calculating the N-gain, while qualitative data were analyzed descriptively to describe students’ activities during the learning process. The results showed an improvement in students’ learning outcomes after the implementation of the teaching aids, with the mean score increasing from 43.4 on the pretest to 87.6 on the posttest, while the N-gain was categorized as high. The observation results also indicated that students became more active in using the teaching aids, collaborating, and participating in learning activities. Thus, plastic waste-based teaching aids were effective in supporting the improvement of mathematics learning outcomes while creating concrete, contextual, and environmentally friendly learning. ABSTRAK Penelitian ini dilaksanakan berdasarkan hasil observasi awal pada pembelajaran matematika peserta didik kelas V di SD Negeri 1 Jatianom. Hasil observasi menunjukkan bahwa hasil belajar matematika peserta didik masih belum optimal, khususnya pada materi penjumlahan bilangan pecahan, serta penggunaan media pembelajaran konkret belum dimanfaatkan secara optimal. Oleh karena itu, penelitian ini bertujuan untuk mengetahui efektivitas alat peraga berbahan limbah plastik terhadap peningkatan hasil belajar matematika peserta didik. Penelitian ini menggunakan metode mixed method dengan desain one-group pretest-posttest pada data kuantitatif dan observasi pembelajaran sebagai data kualitatif. Subjek penelitian terdiri atas 20 peserta didik kelas V yang dipilih menggunakan teknik total sampling. Data dikumpulkan melalui tes hasil belajar dan observasi aktivitas peserta didik selama penerapan alat peraga limbah plastik. Data kuantitatif dianalisis melalui perbandingan hasil pretest dan posttest serta N-gain, sedangkan data kualitatif dianalisis secara deskriptif untuk menggambarkan aktivitas peserta didik selama pembelajaran. Hasil penelitian menunjukkan adanya peningkatan hasil belajar setelah penerapan alat peraga limbah plastik, dengan rata-rata nilai meningkat dari 43,4 pada pretest menjadi 87,6 pada posttest dan peningkatan N-gain berada pada kategori tinggi. Hasil observasi juga menunjukkan bahwa peserta didik lebih aktif menggunakan alat peraga, bekerja sama, dan mengikuti kegiatan pembelajaran. Dengan demikian, alat peraga limbah plastik efektif mendukung peningkatan hasil belajar matematika sekaligus menciptakan pembelajaran yang konkret, kontekstual, dan ramah lingkungan. ]]>
