Treatment fidelity
To control the treatment we used a five-point Likert item: "Before i agreed or disagree with statement ( to task-specific interest), I have solved the problems" Mean and standard deviations were for group one and two 4.3(1.17) and 2.19(1.01) respectively. An unpaired t test showed that there were significant mean differences between both group.As intended in the study, student of group 1 solved the tasks significantly more often than student of group 2 before they reported on their task-specific interest.