In education, representing three‐dimensional objects on a two‐dimensional display surface is a frequent requirement. SIGAD is an interactive system to help students to build drawings, which involve points, segments, vectors, lines and planes. The originality of the system lies in the fact that each figure can be defined by its geometric relations with other figures. The system was designed for the non‐specialist user and the student‐computer dialogue has been chosen to be friendly, efficient and natural.