“…A preprocessing task is conducted before using the approach described in Toledo-Alvarado, Guzmán-Arenas, and Martínez-Luna (2012) to obtain the concepts for each LO. To extract the concepts, each LO is treated as a document, and the top five LOs ranked by Equation (1) are considered the minimum support (see Toledo-Alvarado et al., 2012, for further details). The result of this step is a hierarchy of concepts, which are mapped onto each LO item; thus, the relationships among the items are identical among the concepts in the hierarchy (see Figure 2).…”