The enigmatic question of time, essentially of a physical, psychological and social nature, occupied human since becoming aware of his existence and of the surrounding environment. Young students' conceptions may be a starting point for improving their understanding of the world. This research is interested in very young students who are in full "construction" of the concept of time. Conceptions related to time notion play a decisive role throughout learning procedure and are often incompatible with the scientific model. Conceptions' analysis is a tool for the advancement of a proximal development zone in which a first conceptual system can be built by students. We refer to the area of current or potential success of young students concerning the understanding of time notion. This paper presents findings on 5 to 7-year-old students' conceptions about the inverse relationship between time and speed. Keywords conceptions, students 5 to 7 years old, time, speed, methodology, qualitative analysis