Problem-Based Worksheets Integrated with Corn Cob Adsorbent Experiments in Chemistry Education

This study aims to analyze students' ability to complete problem-based worksheets, analyze critical thinking skills, and describe the effect of adding corn cob adsorbents on the free fatty acid content in used cooking oil. The method used is pre-experimental with a one-shot case study design. Research instruments include observation sheets, problem-based worksheets, and critical thinking skills tests. The results showed that the average ability of students in learning with problem-based worksheets reached a score of 92 (very good), and students' critical thinking skills increased with an average score of 77.72 (good). In addition, the addition of corn cob adsorbent to used cooking oil reduced the free fatty acid content from 0.53% (without treatment) to 0.26%, compared to the addition of zeolite activated carbon, which reduced it to 0.34%. This shows that corn cob adsorbent is effective in reducing the free fatty acid content in used cooking oil.