EN
The paper presents a quasi-experimental study clarifying the variability of maths teachers’ sense of self-efficacy based on their personal theories regarding differences in mathematical giftedness between girls and boys. Didactic self-efficacy is understood as a judgment of the possibility of teaching all learners. A ‘personal theory’ is understood as a verbalized group of judgments regarding the source of mathematical giftedness among girls and boys. The two variables, i.e. ‘personal theories’ and ‘biological sex’, were introduced in a two-factor NOVA model. A strong main effect for ‘personal theories’ was noted, while there was no statistically significant effect for biological sex. The result shows that gender stereotypes can weaken teachers’ sense of didactic self-efficacy, and consequently block pupils’ opportunity for development.