This study aims to analyze the effect of the Project Based Learning (PjBL) model assisted by interactive E-LKPD based on Belale local wisdom on the understanding of environmental concepts of fifth grade elementary school students in the science subject of environmental change. The study used a quasi-experimental nonequivalent control group design. The research subjects were 39 fifth grade students of SDN 24 Singkawang who were divided into two classes: the experimental class (n=20) who received PjBL learning assisted by interactive E-LKPD based on Belale local wisdom, and the control class (n=19) who received conventional learning. The instrument was an environmental concept understanding test consisting of 20 multiple choice questions. Data were analyzed using descriptive statistics, paired sample t-test, independent sample t-test, and effect size (Cohen's d). The results showed that: (1) there was a significant difference between the pretest and posttest in the experimental group (t=6.18; p=0.000; d=1.38) with an N-Gain of 0.63 (moderate category); (2) there was a significant difference between the posttest of the experimental group and the control group (t=4.13; p=0.000; d=1.33); and (3) the average posttest of the experimental group (81.75) was higher than that of the control group (59.74). The PjBL model assisted by interactive E-LKPD based on Belale local wisdom had a significant effect on increasing the understanding of environmental concepts of fifth grade elementary school students. The results of this study imply that the PjBL model assisted by interactive E-LKPD based on Belale local wisdom has been empirically proven to be superior to conventional learning, thus becoming a foundation for the development of innovative and contextual science learning.