Furthermore, for assimilation of the new topics, the so-called application or verbal problem are assigned. Although these problems are described in terms of the world of reality, they are usually so well structured they have one definite answer. For example, in the case of problems about shopping, the cost is assumed to be proportional to the number purchased and 3 dollars each in a problem actually indicates a special case of a proportional relation between two variables. In the world of reality, this proportionality is a mathematical model agreed to by both sides (buyer and seller) that might be subject to change, as in the example of the purchase of a large number of the item. In the so-called application problems, such a situation would never arise because the shopping situation is used only as a situation in which to apply simple multiplication or division. The situation used in the application problems may then be a quasi model. The course actually taught may not start from (g) as a mathematical model but rather may proceed from (e) to (g’) to (j) by substituting the quasi model g’ for g. In other words, it aims at the assimilation of quasi model as a typical example.