This paper explores the correlation between school factors and the differentiated results on sexual behavior between boys and girls in Bogota. A school stratified propensity score matching was performed to match each boy of the sample with the most similar girls in individual, household and school characteristics. A regression analysis was performed to estimate the correlation between school factors and the main outcomes, namely sexual status, condom use in last intercourse, teenage childbearing and age at first intercourse. Boys - in relation to girls - begin earlier their sexual life, report larger use of condom and lower incidence of teenage childbearing. These differences are correlated with sex education at school, and teacher’s characteristics: age, education level and pedagogy degree. The results suggest that the content of sex education that is delivered to girls at school is not complete or accurate and that teachers play a key role to reduce this gender bias.