In practice, Thailand has experience of learning in classroom, especially the measurement and evaluation on mathematical thinking, skills and processes. Concerning the development of system of measurement and evaluation in the past, although there were some researches which gave importance on the development of models for measuring and evaluating students’ learning, those models always emphasized on the contexts that were not at fundamental academic level, or if there were some researches which did so, they frequently created the holistic pictures of the model for every subject, not specifically for mathematics which were different from other subjects. Furthermore, the model sometimes did not correlate with the standards set in the Basic Education Core Curriculum 2008. Hence, it is a challenge for Thailand to solve this problem. The learner should acquire full development in all aspects: knowledge, mathematical skills and processes, and desirable. Therefore, the objectives of the study were to: 1) develop a mathematics classroom assessment model for the demonstration schools of the Office of Higher Education Commission, and 2) investigate the quality of the model according to its utility, feasibility, propriety, and accuracy with the effects. The outcome from these three groups of people (students, teachers, and administrators). This study was an exploration research using a questionnaire that was corrected and checked by the experts. The data were collected from 120 teachers at 14 schools who were teaching at secondary level and were working under the jurisdiction of the Office of Higher Education. The model for measuring and evaluating students’ learning was called a collaborative pyramid assessment, consisting of 4 dimensions of assessment: 1) collaborative plan assessment, 2) collaborative gather evidence, 3) collaborative interpret evidence, and 4) collaborative use results. There were four operational steps within each dimension: 1) knowledge, 2) thinking, 3) mathematical skills and processes, and 4) desirable attribute. The results from the implementations of this model provided ways for demonstration school teachers to do measurement and evaluation in the mathematics classroom appropriately.