Abstract: This study aims to produce science teaching materials products and related devices such as Learning Implementation Plans (RPP), Student Activity Sheets (LKS), and Test Sheets that are valid, practical, and effective to improve critical thinking of elementary school students. This research was carried out using the 4-D model of Thiagarajan et al., Namely the stage of defining, designing, developing, disseminating and testing in the fifth grade of Dukuhtunggal State Elementary School, Duduklor State Elementary School, Margoanyar Lamongan State Elementary School year 2018/2019 teaching with One-Group Pretest-Posttest Design.