Alternative conceptions about proportional reasoning in high school students

This study aimed to identify alternative conceptions about proportional reasoning among High School Students at a public school located in the state of Guerrero, Mexico. Using a qualitative approach, data were collected through task-based interviews with fifteen students 12th-grade students. Data were analyzed using the thematic analysis method. The findings allowed to identify five alternative conceptions: (1) the variational behavior of a line graph indicates the type of proportional variation; (2) the constant function algebraically represents a proportional variation; (3) a negative slope in the equation of a line indicates an inverse proportional variation; (4) direct proportional variation is conceived as an object; and (5) the constant of proportionality in the graph of a direct proportional variation is interpreted as the length of the line. While this study does not incorporate data from teachers, the findings indicate that instructional strategies prioritizing procedural techniques rather than conceptual understanding. Additional research is required to investigate how teachers' knowledge and instructional methods influence students' development of proportional reasoning. In the same line, the results highlight the need to design instructional strategies that promote the development of more robust proportional reasoning in the High School level.