This study was conducted to examine the effects of play activities on computation ability in the cognitive aspect and mathematical attitude in the affective aspect. The subjects were three 4th grade students who were considered to be mathematical low-achieving students at S elementary school in Seoul city. Their overall IQ scores were more than 80 for K-WISC-Ⅲ and less than 15% for the BASA Math test. As measuring instruments, BASA Math and mathematical attitude test were used. CBM(Curriculum-Based Measurement) procedure was used to perform this study. This study was divided into three different phases: baseline, intervention and maintenance. For each activity, formative evaluation results were plotted on a graph to observe the students\' progress. The difference between the mathematical attitudes was analyzed and compared by keeping on pre-test and post-test. The first result is the play activities helped improve the students\' addition and subtraction ability, which required mathematical computation ability. Second, these activities were found to be effective as an instruction method, which changed mathematical low-achieving students to have a positive attitude towards the realm of affective mathematics. Considered to this fact, in addition to an increase of play activities frequency or the variety of play methods, presenting play activities with using not just one teaching tool but also various tools was necessary. Key words : Learning Disabilities, play activities, CBM, BASA: MATH