After the previous assignment, our instructures wanted us to produce a diagram of it. It was something new for us. We started to producing it and after that they wanted us to make a model with the same units but one element of that unit should be streched and also we should have be in accordance with that diagram. I tried a lot to reach that model but I couldn’t. And then, I realized that the diagram was so specific to that previous model. So that, I tried to produce a generic diagram as possible and I tried to make units grouped according to their relations. This time it was lots more easy. So that I could reach this model. In addition, stretching operation made me gain new relations even though I lost some of them. It was a good experience that taught me lot of useful things.