The idea behind the two measures is that raw achievement is desired but schools should get credit for growing students who start at a lower level, perhaps because of poverty or some other liability. The education agency has been shifting the value of these two measures in the overall report card, with growth counting for more and more each year and achievement counting for less.
The Index can be complicated, and GOSA has broken it down with a simple scale that any parent can probably relate to: schools get a letter grade of “A” through “F” based on their CCRPI score. The site contains additional information for parents who want to drill down and read about student demographics or test performance in particular subjects, such as English and math. The site also allows comparisons between schools, districts and the state.