The study was divided into several levels: kindergarten, primary, secondary and university levels, each of which will be divided into levels, easy to difficult levels.
The study is divided into several levels: kindergarten primary school and University, where each level, they are divided into levels of easy to difficult.
The study was divided into a multi-level is the level kindergarten elementary middle school and college level, each of which will be divided into a level of difficulty to be easy-to-level