The activity below was carried through with the pupils. Considered exercises) It constructs a triangle with a straight angle. b) It constructs to a triangle with three sides de5 centimeters. c) It constructs a triangle that has a side de5 centimeters, an angle of 20 and another angle of 70. d) It constructs a triangle with angles of 60, 100 and 40. From these exercises, pupils had been inquired to perceive what he happens with the triangle of letter d. Then, the teacher considered a constructive debate so that the pupils argued on the main characteristics of this triangle in relation to its angles. Of this form, the necessity exists of that the professors stimulate the debate to assist the pupils to explore the theorem of the addition of the internal angles of a triangle as well as other angular properties of this geometric figure.

Presentation and Analysis of the Results Steps (2000) affirm that the pupils represent and construct the space through the interpretation, manipulation and interaction with the way in which they are inserted. With this perspective, the mental images constructed by the pupils intervene with its geometric visualization. Then, the geometry education is essential in the first years of escolarizao, therefore it facilitates and it promotes the contact of the pupils with the geometric elements. The constructions of space and of the geometric concepts leads to a gradual process of preparation of the pupils, therefore only the explanation of the professors would not be enough for the acquisition of this geometric knowledge. The activities developed in this project had allowed that the pupils passed of a level of understanding for another one as its geometric maturity. Of this form, with an appropriate education they had evolved sequentially for the other superior levels of geometric conceptual understanding. However, Steps (2000) argue that we must take care with this boarding, therefore an education of superior geometry to the level of agreement of the pupils can hinder the progress and compromise the understanding of the geometric content of these pupils.