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.

Recently, in Indonesia, project-based learning (PjBL) has been used as an alternative approach in the teaching and learning process. Research on PjBL has been widely conducted in many countries at various levels. In most previous studies, PjBL was used to improve students' competence in certain math subjects. This study uses a case study research method to determine the effectiveness of PjBL at university in improving pre-service teachers' PCK. The research was carried out in 2022 involving fourteen mathematics education study program students selected by purposive sampling. The instruments used consisted of observation sheets, tests, and questionnaires. During the PjBL activity, participants were given a project to develop teaching materials for geometric transformation using certain teaching-learning strategies. The results of the study show that PjBL can improve students' PCK ability, although participants face several obstacles related to commitment to completing projects on time. Therefore, PjBL can be applied in the teaching-learning process to support professional mathematics teachers.