3.1. Participants
In this study 18 different public schools were randomly selected from Athens metropolitan area. Students of different intellectual abil-
ity, gender, economic status, etc constituting one whole classroom from each school took part in the two samples. A total of 179 children
participated in the research and specifically 102 in the first sample and 77 in the second one. They all were fifth graders with a mean age of
11 years. The pupils joined the research only after their school teachers, parents and they consented.