Fig. 1

Reading comprehension and mathematics achievement for second-graders according to the level of socio-economic status approximated by the highest level of parents’ education (pared). The family background predictor has been divided into three classes: disadvantaged students, those having parents with years of schooling between 4 and 10; students with average living standards having parents with years of education in the interval [11, 15) and advantaged students whose parents have more than 15 years of education. The vertical dotted lines represent the group averages