Attention to students cognitive states is an important issue in educational research. Educational research as well as testing practises generally is however dependent on communicative work in order to achive a credible picture of how the student perceive the teaching subject. The purpose in this paper is to study sequences of interaction produced in research interwievs with 14 year math students, designed to capture students thinking on school maths. The interwievs are designed as post-lesson interwievs after the lesson. The analysis of these research interwievs shows that talk on student thinking math is not a neutral medium and that the interaction has obvious similarities with teachers student interaction (IRE). This study also has implications for general educational questions concering teachers possibilities to validiate the knowledge of students in the classroom interaction.