The purpose of this study is to show the effectiveness of classroom teaching for better geometrization skills. The author developed a problem involving a traffic accident caused by a wide blind zone, devised a means of geometrization for the relation among several phenomena, and practiced it with first grade junior high school students. The results showed it to be effective; students could represent the blind zone rightly by the means devised, and became able to draw more abstract geometrical figures. Moreover it was found that almost all of the students managed to solve real-world problems through mathematical modelling.
