Abstract
The paper studies types of teacher's hidden incentives (in Brousseau's Theory of Didactical Situations called Topaze effect) in teaching mathematics. The method used is the method of multiple case study.
Transcripts of communication between two teachers (from two schools) and their 14-15 years old pupils in ten consecutive lessons of mathematics are analysed. Several types of explicit (overt) and implicit (covert) teacher's prompting are detected.
The study characterizes and illustrates these types of a teacher's behaviour (Topaze effect) using examples of classroom dialogue and makes conjectures about their reasons. The influence of Topaze effect on quality of pupils' understanding of mathematics and cultivation of (mathematical) thinking is discussed.