The problem of this study was to measure, to compare, and to analyze the amount of stress, as indicated by heartbeat rate, experienced by students during teaching-learning activities in sixth-grade mathematics in a regular classroom. The bases for comparison were the heartbeat rates of selected students as recorded by a cardiotachometer and achievement scores on pretests and posttests dealing with verbal problems. All data were analyzed using the t-tests for the significance of the difference between the means. Findings of the study showed that students did experience increased heartbeat rates while solving verbal problems in sixth-grade mathematics. Also, during the teaching-learning activities, students who solved verbal problems using the realistic approach did not experience more stress than students who solved problems using the standard approach. The standard group did not perform significantly better than the realistic group on the standard pretest-posttest. However, students who were involved in the realistic method achieved better on all types of problems than did students who were taught by the standard method.