The nine indicates very strong academic performance. It means that your school's API score ranked among the top 20 percent of all the schools in the state. The similar-schools ranking compares the API scores of "like schools"—the 100 schools considered most similar to yours, based on a complex calculation of demographic and socioeconomic indicators: the level of the parents' education; the percentage of students qualifying for free or reduced lunch; the percentage of students learning English; the racial makeup of the student population; the number of teachers with full or emergency credentials; whether it's a year-round school; the mobility of the student population; and the average class size. The first two indicators in that list tend to have the most impact on any school's academic achievement. A one on the similar-schools ranking means that your school's API score is in the bottom ten percent of those schools considered most similar to yours. Sometimes the total range of scores among similar schools is quite small, so the difference between scores might be smaller than it sounds. Sometimes those differences are more significant. Your school's API ranking means that it's among the best-scoring schools in the state. However, watch the similar-schools ranking over several years. (Be aware that the schools in that group can change yearly as demographics and other indicators change, both at your school and at the others.) You want to see that score improve over time. If your school consistently ranks at the bottom compared to other schools most like it, you should wonder why. But don't blame the ranking on one factor, such as a group of teachers who aren't fully credentialed. They may be the most dynamic teachers on staff. Your school's administration would need to carefully evaluate the whole educational atmosphere to figure out what's going on.