The primary aim of this work is to investigate the "emotional dimension" as a criterion for evaluating an educational music software called Tactus. In order to collect data, two training sessions were carried out with volunteer students (N=45) in specialized music education at three Chilean institutions. After, an evaluation was carried out using an assessment instrument, which was devised to determine the emotions, both positive and negative, which come into play when a student uses Tactus, and thereby measure the emotional dimension to determine the quality of the program in the affective domain. This instrument, a checklist of positive and negative emotions, was completed as part of a student/user report, included in a more global evaluation questionnaire completed at the end of the two weeklong training sessions with Tactus. The positive results confirm previous, other traditional assessments that describe Tactus as a useful support tool for teaching rhythm in educational environments. The results of this study also suggest that that evaluation of the emotional dimension may be useful in the general scope of the evaluation of educational software.