Graph problems as a means for accessing the abstraction skills

International audienceComputational thinking is an important 21 st century skill. The ability to design own algorithm, i.e. algorithmic thinking is its integral part. Graph algorithms seem to be a promising mathematical content contributing to development of algorithmic thinking. However, in order to apply the corresponding skills to the problem at hand, first a corresponding representations has to be found. This step of abstraction is crucial for the application of skills to unknown situations and can be seen as a prerequisite for the algorithmic thinking. Solutions of the representation problem of 58 undergraduate students were analysed. Most students chose the diagram as a representation of the situation, only three students used the adjacency matrix and no students chose the incidence matrix or adjacency list, the other known representations. This may indicate that more activities are needed for enhancing students' ability to represent the graph, either by matrices or by a diagram