This quantitative study aimed to determine the level of acceptability of the developed and validated instructional materials in teaching fraction among the Grade 5 pupils who are officially enrolled in Pis-anan Central School, District of Sibalom South, School Year 2023-2024. In this study, the design-based research using the analysis, design, development, implementation, and evaluation (ADDIE) model, which involve the process of developing and validating the instructional materials in teaching fraction. The respondents of the study were all the 47 Grade 5 pupils officially enrolled in Pis-anan Central School. Data collection strategies employed was design-based research using the ADDIE model. Data were gathered using the researcher-made instrument on instructional materials in solving fraction duly validated by the experts. Data were analyzed using the Statistical Packages for Social Sciences (SPSS) version 22. The findings of the study revealed while grade 5 pupils performed well in solving addition and subtraction fraction problems, they struggled with creating problems, particularly those involving division and multiple operations. The implementation of specially designed instructional materials addressing these least mastered competencies led to significant improvements in pupils’ mastery levels of fraction operations, as evidenced by pre and posttest comparisons. Moreover, the instructional materials were highly accepted for their content quality and effectiveness in enhancing understanding and problem-solving abilities in fractions.