The statistical pool of the current research was all the elementary students in the city of Tehran studying in the
academic year of 2009-2010. the sample volume of the students in this research was 2016 and it was attained by using the sample volume formula. In order to gather data, in the beginning, based on the prevalent method, Tehran was divided into three affluent, semi-affluent and poor regions as such that regions 1-2-3and 6 were considered to be affluent, regions 4-5-7-9-10-11-12 and 13 were considered to be semi-affluent and regions 14- 15-16-17-18 and 19 as the poor neighborhood. Then, in every category two regions were randomly selected in which a total of the following regions: 2,6,13,5,17 and 17 were selected. In the following stage, a list of elementary schools was attained from the board of education’s administration office in each region. In each region two girls and two boys schools were randomly selected. In the next stage, 2016 students were randomly selected by going to schools and getting the class lists of different grades.