Figure 1. Modelling Cycle [11]
Firstly, the problem situation should be understood by the student, that is to say, "the situation model" is formed. After that, the situation is structured and turned into "a real model". The student should decide especially on what is worth doing at this point. During the mathematizing process, which corresponds to the third step, the student turns "the real model" into a "mathematical model". The student conducts "a mathematical work (calculation, solving inequalities etc.)" and reaches "the mathematical results" at the fourth step. Real results in the daily life are interpreted and verified during the fifth step. Finally the possible solutions of the problem are presented and suggestions are made regarding the problem.
According to Galbraith (1989), there are 3 different teaching approaches in modelling. These are as follows:
1) "General application approach" focuses on a certain application. Generally, the teacher introduces the model and the students use the model in a controlled manner. This approach is mostly used in secondary schools and it includes 4th (calculation, solving inequalities etc.) and 5th steps (real results in the daily life are interpreted and verified) of the modeling process.
2) "Structure modeling approach" uses the real life situations and covers all the stages of the modeling process form the 1st stage (the problem situation should be understood by the student) to the 7th stage (the possible solutions of the problem are presented). The teacher makes an important effort to make mathematical model used in the 3rd stage (mathematizing process).
3) "Open modeling approach". In this approach, students work with the limited help of the teacher about the problem that is given because teacher does not have to control the students. This approach is not used widely [25].
2. Mathematical Modeling Activity and Activity Samples
Mathematical modelling activities are mathematical modeling conducted by students in the classroom environment. The students, who work in small groups during these activities, develop the mathematical interpretations of the problem situations on their own and mathematizing the situations that are given. These activities are developed within the framework of the themes the children are interested in and they are organized in a way that will encourage children to study and clarify the problem situation. At the end of modeling activities, the students present the models they developed to their friends using various illustration systems such as written symbols, verbal reports, diagrams on paper or pictures [9].
As an example of modeling activities, "big foot problem", which is a problem situation regarding real life and which is adapted by Lesh and Doerr (2003a) to the second level of primary education . This modeling activity is organized as follows:
Model Example
“The Giant's Shoe”
There is a pair of shoes in a sport center in the Philippines. According to Guinness Book of the World Records, it is the largest shoe of the world with the width of 2.37 m and the length of 5.29 m. What is the height of the giant that could actually wear these shoes?