Calls for increased student involvement in mathematics classroom learning situations are due primarily to the recognition that a traditional lecture/demonstration format within school mathematics instruction is not effective in fostering and promoting students' problem-solving abilities, mathematical reasoning power, and mathematical communication skills. In an attempt to come to a better understanding of mathematics classroom learning, a study focused on the particular activity of mathematical discourse, with the main goal being both the characterization of the potential learning opportunities and the inference of students' construction of mathematical meanings. The participants in this study were the students and teacher in a third-grade class of a laboratory school associated with a Southern university, chosen to reflect the gender, socioeconomic status, ability levels, and ethnicity of the State. Various qualitative research techniques such as participant observations, interviews, and video recordings were used to collect data, which were categorized according to style and meaning of class participation. Results indicate that classroom mathematical discourse is a rich environment for both student growth and mathematical learning, which was confirmed by more elaborate and integrated schema for mathematical reasoning and problem solving. (22 references) (JJK)