Sobre pensamento geomátrico, provas e demonstrações matemáticas de alunos do 2º ano do Ensino Médio nos ambientes Lápis e Papel e Geogebra

Abstract

Our research work aimed to investigate what type of proof, mathematical demonstration and level of geometrical thinking can occur from a didactic proposal within pencil, paper and GeoGebra environments. As qualitative research and study case, we used as instruments essays with Mathematical Proof and Demonstration themes, a didactic proposal developed by a team of five people who inserted worked collaboratively in the CAPES/OBEDUC/UFMS/UEPB/UFAL Project, field notes, participant observation, audios and photos. We elaborated a didactic proposal with eighteen activities, divided into four parts, which encouraged the students to reflect, justify, prove and demonstrate. The proposal application was carried out in July 2015 with High School 2nd year students of a public school in the town of Areia, Paraíba. For such, the students organized themselves in couples and one trio and the data collection happened in three moments. In the first moment we applied the essay, revised angles, triangles and theorems with the students and worked GeoGebra application with them. In the second moment we applied Parts I and II of the proposal with eight activities on Pythagoras Theorem and three activities on Sum of the Internal Angles of a Triangle Theorem, respectively. In the third moment we applied Part III, with two questions on External Angle Theorem and Part IV, with five question to be worked with the GeoGebra application on Pythagoras Theorem and Sum of the Internal Angles of a Triangle Theorem. In our research work we analyzed the work developed by the trio of students, once they were great in responding all the questions/activities. We analyzed Activity 8 of Part I, Activity 1 and 2 of Part II and all Activities of Part IV, totalizing in eight questions. We used the triangulation method for our study case and, firstly, we traced the profiles of the trio in relation to Mathematical Proof and Demonstration. Then we investigated the geometric thinking and the mathematical proof and demonstration used by the trio of students in the pencil and paper and GeoGebra environments. For such, we used discussions around the level of geometrical thinking proposed by Parzysz (2006) and the type of proofs proposed by Balacheff (2000) and Nasser and Tinoco (2003). From our research results we could conclude that the trio of students could not develop the justifications or proofs, once they did not understand what are mathematical proof and demonstration are, in their essays they understand mathematical proofs as bimestrial evaluations applied by the mathematics teacher. Moreover, the mathematical proofs performed by these students were in accordance with naive empiricism, pragmatic proof (Balacheff, 2000) and graphic justification (Nassar and Tinoco, 2003). In this way, when we observed the students geometrical thinking (Parzysz, 2006) we noted that it fits into two levels of the non-axiomatic Geometry: the Concrete Geomety (G0) and the Spatio-Graphique Geometry (G1), once these students used drawings to justify their affirmations, as the validation of the affirmation was done by the trio. We believe that if in Mathematic classes the teachers contemplate mathematical proof and demonstration, respecting the level of education, the degree of knowledge and maturity of the students, they could strongly contribute to the process of teaching and learning Mathematics and geometrical thinking, once the students would be led to reflect, justify, prove and demonstrate their ideas.