This study examines which factors in the behaviour of math teachers in their contact with high school students contribute to the developing, worsening or alleviating of math anxiety during mathematics activities.
The study was conducted in the form of a survey involving $888$ high school students during their math lesson. The survey included several scenarios corresponding to the behaviour of math teachers to which the students could indicate their level of stress. Results show that students indicated to feel significantly higher levels of stress in a scenario where a teacher shows her belief in the growth mindset by forcing a student to try an exercise again after failing once, in comparison with a teacher who shows her belief in the fixed mindset by stating that some students remain to have difficulties with math. In addition, the students indicated to feel significantly lower levels of stress when the teacher writes down the correct answer in their book immediately. The effect sizes of these differences are small and moderate, respectively. Furthermore, it was found that students indicated to feel significantly lower levels of stress, with moderate effect sizes, when a teacher evaluates their work by writing down hints, instead of drawing lines through their mistakes or grading their work in a formative manner. Another important finding of this study was the significantly higher levels of stress students indicated in a scenario where the teacher shows her belief in the fixed mindset by concluding after a few mistakes that a student finds mathematics difficult in general, in comparison with a teacher showing her belief in the growth mindset by emphasizing the learning goal. In conclusion, this study suggests that students might not be experienced in handling exercises alone and feel higher levels of stress when they are forced to do so, even though the teacher shows her belief in the growth mindset.