Tables are a presentation format that is commonly used to organize information, and they are widely present in many scenarios of our students' everyday activities; however, there is a scarcity of studies devoted to their analysis. Some of these studies point out that the organization of data into a double-entry table presents difficulties for primary and secondary school students. The present study analyzes the following: (1) the level of competency of primary and secondary school students in constructing a double-entry table from a set of data and (2) the main difficulties encountered by these students during the task. Our findings showed that the percentage of middle-school students who succeeded in constructing a conventional table was relatively low, and the number did not significantly increase over four school years. A set of difficulties is identified and discussed in terms of cognitive and graphical processes.