This research is motivated by the Problem Based Learning model, which is
not always certain to be tested, can affect students' Mathematics learning
achievement. This study aimed to examine the effect of the Problem-Based Learning
model on students' mathematics learning achievement. The method used Pre-
Experimental Design with the One-Group Pretest-Posttest Design. The population
in this study were all fourth-grade B students with non-probability sampling with a
saturated sampling technique. The sample in this study amounted to 20 students.
The instruments used were pretest and posttest to measure student achievement
before and after treatment. Data analysis used the Paired Sample t-Test. The results
of the research hypothesis testing using the SPSS version 24 program show the
value of Sig. 0.000 < 0.025, meaning that there is an effect of the Problem-Based
Learning model on mathematics learning achievement.