This study attempted to develop a literature-informed discourse-based instructional approach and evaluated its effects on eleventh-grade students' conceptual and procedural understandings in probability and statistics. To this end, a quasi-experimental study that involved two control groups and one experimental group was used. One-way analysis of variance of the baseline data showed that the three groups were comparable at the start of the experiment. After the intervention, the Kruskal-Wallis test analysis performed on the posttest data showed significant differences in conceptual understanding and procedural understanding. Pairwise comparisons of the three groups using Dunn's test as post-hoc analysis showed that students who underwent discourse-based instruction demonstrated a better understanding of probability and statistics compared to those students who received traditional instruction. The analysis of survey data about students' learning mathematics through discourse provided an insight into how the intervention strategy helped students improve their learning. Overall, the main finding of the study is that discourse-based instruction enables students to develop a better understanding of mathematical topics when appropriately orchestrated interactive discourse practices occur. The study contributes a discourse-based instructional design framework and empirical evidence to the field of knowledge of teaching approaches. The findings may motivate educators to examine students' textbooks for mathematical discourse considerations. A possible recommendation for future research would be conducting longitudinal studies to explore the relations between students' conceptual understanding and procedural understanding in a specific domain of mathematics and to examine how discourse-based instruction affects the relations between conceptual and procedural knowledge.