Investigating industrial vocational high school students’ understanding of the function concept

The present study aimed to investigate students’ understanding of the function concept and their ability to classify relations as functions and non-functions. The participants of the study were 130 tenth grade industrial vocational high school students. The data were collected through a two-part test and semi-structured interviews with ten students. While the first part of the test consisted of a set correspondence relation and some questions related to this relation, the second part consisted of relations given in algebraic expressions, graphs, and set of ordered pairs. The data were analyzed by using content analysis. The results suggest that students mostly defined function as “feature”. Many of the students were unable to apply definition of a function to classify relations into functions and non-functions. In addition, they had difficulties with defining domain, range, and image sets of functions, and forming (pre-image, image) pairs.