We started this study after noticing that university students make certain mistakes when elaborating column charts. The objectives of our research were to: 1) analyse the knowledge integrated into the competence of elaborating column charts; 2) analyse the procedure(s) to elaborate these charts; 3) analyse the mistakes that university students make in elaborating these charts; 4) analyse the causes leading to their mistakes; 5) identify ways to improve the educational process and students' performance results. In order to achieve these objectives, we studied the activity for forming students' competence to elaborate column charts and we analysed 704 such charts realised by 410 students at the Faculty of Geography within the University of Bucharest, Romania, during the 2010-2011 and 2011-2012 academic years. In this paper, we describe the competence to elaborate column charts and present an analytical assessment grid with a dichotomous scale according to the way of presentation proposed by Maria Eliza Dulama. In the analysis, we assessed charts using this assessment grid that included 20 criteria. We conclude by proposing ways to better the activity that underlies the formation of elaborating column charts (e.g. discussing chart types with students, discussing mistakes and how to correct them, discussing causes of their mistakes and an assessment grid before elaborating charts, creating a check list, etc.).