Fourth grade students of SD Negeri Jarit 01 Pasirian subdistrict Lumajang Regency have difficulty in understanding the learning materials in the IPAS content so that it has an impact on low learning outcomes. The difficulties experienced were caused by the use of monotonous learning methods and the lack of interest of students in learning science content materials. This study was conducted with the aim to improve the learning outcomes of students both from the aspect of knowledge, skills, and attitudes through the application of problem based learning (PBL) model. The type of research used was collaborative class action research (PTKK) which was carried out for 2 cycles. This study uses qualitative and quantitative approaches. The results showed an increase from cycle I to Cycle II. The percentage of completeness of knowledge aspects of cycle I is 73%, cycle II is 91%. The skill aspect of cycle I is 64%, cycle II is 82%. Aspects of mutual assistance attitude cycle I 64%, cycle II to 86%, critical thinking skills cycle I by 45%, cycle II to 77%.