Learning fractions in elementary school is often challenging because the concepts are abstract and require concrete representations to be understood meaningfully. This quantitative study aims to examine the effect of fraction block media on students’ conceptual understanding in mathematics learning. The research employed a pre-experimental One Group Pretest–Posttest design involving 31 third- grade students selected through total sampling. Data were collected through pretest and posttest assessments and analyzed using prerequisite tests followed by hypothesis testing. The Shapiro–Wilk test indicated that both pretest and posttest scores were normally distributed (sig > 0.05), and Levene’s test showed homogeneous variances (sig > 0.05). Based on these results, the hypothesis was tested using a paired sample t-test. The findings revealed a significant difference between pretest and posttest scores, with a p-value of 0.000 (p < 0.05) and an increase in the mean score from 45.48 to 90.84. These results demonstrate that fraction block media has a significant effect on improving students’ conceptual understanding of fractions. This study suggests that teachers should incorporate concrete instructional media to enhance students’ understanding of mathematical concepts in elementary school.