One of the challenging concepts that many primary school pupils deal with is adding fractions. However, the problem of adding fractions in the classroom might be resolved by employing virtual manipulatives. This study aimed to compare the use of virtual manipulatives and conventional lecture-based methods in two groups of Year 4 pupils to examine the effects of understanding the addition of fractions. Sixty-four pupils participated in this study. This study occurred throughout a six-week time frame in a primary school in Temerloh, Malaysia. A quasi-experimental non-equivalent pre-post test was implemented to compare the effects of the control and experimental groups. The first finding showed that the experimental group's conceptual understanding of adding fractions was significantly better after using virtual manipulatives during the intervention, t (62) = 11.682, p<0.005. Cohen's D demonstrated the effect size for comparison (d=2.06), showing a significant effect. The second finding revealed that the conceptual understanding of adding fractions was significantly better after the intervention with virtual manipulatives when controlling the pre-test score, F (1, 61) = 9.475, p < .001, η2 = 0.134. This study showed that pupils in the experimental group improved their conceptual understanding of adding fractions.