As recent findings suggest, the education of future secondary school teachers seems to be in need of improvement. For the subject of mathematics, the present study aimed to develop and evaluate teaching innovations based on theoretical principles of effective learning and instruction in mathematics in higher education. The innovations were mainly implemented in the tutorials accompanying an introductory lecture. Specifically, the innovations were meant to improve both the content and the pedagogical content knowledge of the tutors, with an additional goal of supporting the cognitive activating elements within the tutorials. The measures were evaluated with the help of a quasi-experimental study that compared two cohorts of students. The results indicate that the students benefitted from the teaching innovations, and both the supportiveness and the competence of the tutors were found to be higher in the experimental group. The answers to the weekly homework during the semester were better as well. However, the positive effect was not evident in the final exam at the end of the semester. As a consequence of the teaching innovations, the students also perceived themselves as less competent, which may be linked to a more realistic self-assessment.