This paper proposes a Collaborative Mathematics Teaching and Learning Model (CMTLM) and describes its major elements using a mathematical framework for evaluation. CMTLM is developed for mathematics classrooms in which students are supposed to produce the right answers to problems and provide explanations, comparisons, justifications, identification of errors, and individual proficiency. The proposed model comprises six phases: diagnostic activation, formation of purposeful groups, collaborative problem solving, mathematical discourse and justification, teacher synthesis, and individual-plus-group assessment. In order to quantify the framework, the paper introduces normalized learning gain, group heterogeneity, participation equity, a weighted collaboration index, and model-effectiveness composite score. Mathematical expressions for treatment effect, Cohen’s effect size, analysis of covariance, and reliability are also introduced for future field testing. As an illustration, the quadratic function task is described showing how mathematics can be integrated into the collaborative process. A numerical illustration shows how student pre-test and post-test scores may be transformed into measures of learning gains and collaboration without the use of made-up research results. The design described in this paper is meant to be evaluated through a quasi-experiment using a pre-test post-test design in secondary schools. The paper argues that collaborative teaching of mathematics is researchable if math performance, interaction, equity and accountability are quantitatively measurable variables.