<![CDATA[This study aims to produce differentiated student worksheets that are valid, practical, and effective in improving students' critical thinking skills. The research and development (R&D) design was conducted using the 4-D model, which consists of four steps: define, design, develop, and disseminate. The research subjects were 15 students in a small-scale trial and 66 students in a large-scale trial, all from class XI of SMA Negeri 1 Seputih Surabaya with cluster random sampling. The trial design used by the researcher was a non-equivalent control group design. The instruments used were needs analysis questionnaires, validity questionnaires, practicality questionnaires, learning implementation observation sheets, and pretest-posttest of critical thinking skills. Data analysis techniques for validity and practicality use descriptive percentage analysis, while data analysis for effectiveness uses statistical analysis (independent sample t-test, paired sample t-test and one-way anova). The results of the development research indicate that differentiated student worksheets are highly valid (94%); differentiated student worksheets are practical for improving students' critical thinking skills in terms of learning implementation; differentiated student worksheets were effective in improving students' critical thinking skills with a large effect size (0.99). The conclusion is that differentiated worksheets on the human digestive system have been developed that can improve students' critical thinking skills.]]>
