Paulus Nainggolan and Bornok Sinaga 2023. Development of Learning Videos to Improve Students’ Ability to Understand Mathematical Concepts on Polynomial Material. JURNAL RISET RUMPUN ILMU PENDIDIKAN. 2, 1 (Apr. 2023), 228–239. DOI:https://doi.org/10.55606/jurripen.v2i1.1181.