Young students thinking about motion graphs

This article considers an individual activity given to grade 2 students at the end of a teaching experiment lasted about four months. The students have extensively used a motion sensor to work with graphical representations of position versus time. The activity asks the students to compare two graphs, choosing two cartoon characters, animals, and vehicles, as subjects of possible corresponding motions. Analysing their written arguments, we look at the thinking strategies the students adopt to solve the task. A common factor characterizes these strategies: the meaning of the horizontal straight line in terms of motion modelling is used as a key to the understanding.