The purpose of this study is to develop and produce a product in the form of student worksheets with the guided inquiry method that can be used in the learning process and to improve student learning outcomes. This research was categorized as development research. The research sample taken was the seventh-grade students of SMP Negeri 5 SATAP, East Likupang. The number of students studied was 30 students in the experimental class and 30 students in the control class. In this study, the developed worksheet of students with the guided inquiry method will increase the activeness and knowledge of students. This study uses the development of a 4-D learning device according to Thiagarajan. The development of this model has four stages, namely defining, designing, developing, and disseminating. The data taken from the research is science learning outcomes data measured by cognitive question instruments that have previously been tested for validity and reliability. Hypothesis testing was done by using paired sample t-test analysis with pretest-posttest control group design. The results showed that the development of teaching materials in the form of student worksheets with the guided inquiry method turned out to be able to improve the learning outcomes of class VII students. The development of teaching materials in the form of student worksheets by the guided inquiry method has received a good response from students seen from the aspect of activity with very high criteria and responses of students with very feasible criteria so that they can be applied in the learning process.