Churchman also divides the model into 3 categories as; 1) the real-like model is a model that looks similar to real thing but have different sizes, such as a photo or the model of cars, planes and boats 2) the simulated model is a model that used to represent something, such as the contours line represents the elevation of area and 3) symbolic model is a model that used the texts, numbers or symbols to represent the various parameters and mostly in the form of a mathematical relationship. (10) The model can also be divided into several categories depending on textbooks and related fields.