Uma investigação sobre a razão entre o comprimento e o diâmetro de uma circunferência em sala de aula

This article emphasizes the importance of applying investigative activities in Mathematics classes. In the writing is the script of an activity involving students' notes about the number pi(?) in an 8th grade class, carried in a school in the city of São João do Rio do Peixe- PB. The activity covers the History of Mathematics, which discusses the discovery of the value of ? by ancient civilizations and the mathematical investigation that was carried out in the classroom using concrete materials. At the end of the activity, students obtained approximations for the value of ? and also had the opportunity to analyze their colleagues' answers, leading them to make conjectures, develop hypotheses and give answers to approximate the value of this important and widely used number. in the study of Mathematics.