
In the frame work of Advanced Mathematical Thinking and related to Functions and Graphics topic, we are developing different focused on secondary students (16-18 years) ideas and performance. The main goal of our work is to improve knowledge about students reasoning and strategies used on solving tasks related with graph construction. We analyze 250 students' answers, in two instants (beginning and middle of a course), at a same task of graph construction of a function given by verbal conditions representing a non contextualized situation. We look especially for the use of continuos graphs (versus non continuos ones), for the use of prototypes like straight lines and parabolic and hyperbolic lines. We look also for the changes (evolution) on those uses.