Explaning a table [a short outline: I want to develop my academic writing skills because I will be at an American University in Autumn. I will try to discuss some points from my paper in portuguese in english. I will try to do this without a dictionary.] We present schools characteristics in table 1. There is no difference to the most of index analyzed. In the first part of the table, we present some averages from schools and in the second part we present index from the neighborhoods where schools are installed. Schools are big in all regions and status. All of them have more than one thousand students. Three areas (Sao Paulo, Vale do Paraíba and Porto Alegre) have about half of students in the secondary level and the other half in the elementary. The other two regions (Rio de Janeiro and Belo Horizonte) concentrate enrollment in secondary level. We also can see that many students are enrolled in the night shift. This fact also indicates that schools attend poor socioeconomic background students. We analyze the class size is as well. On average there are more than 35 students by class. Finally, we present some index that are very problematic in Brazilian secondary school: reprobation and dropout rates. They are usually bigger on average. The range of reprobation rates varies between 17\% and 25\%. Dropout rates are between 3.6\% and 21\%. Clearly, these indexes are a serious problem to treated and control schools. It is difficult to imagine a good school that just provide education to a small portion of pupils. The second part of the table analysis the neighborhood index of schools. We took these data from demographic census provided by Brazil. Again it indicates students have a poor socioeconomic background.