Tasks for enriching the understanding of the concept of linear span

International audienceThe concept of linear span is one of the first abstract notions that students encounter in a course on Linear Algebra. Using the theoretical construct of concept image and concept definition (Tall & Vinner, 1981) along with observations about teaching and learning Linear Algebra, we present two tasks designed to enrich students' concept image regarding linear span. These tasks could be included in a problem workshop of an introductory university course on Linear Algebra. Each task is carefully created and/or selected so as to foster the ground for potential conflict factors to arise and be confronted. A preliminary evaluation shows that the tasks are well received by students and succeed in addressing certain conflicting factors