(Faculty of Science and Technology, Rajamangala University of Technology Suvarnabhumi, Suphanburi Campus, Thailand)

Abstract: The objective of the study was to investigate the mathematical understanding of learners based on Constructivist Theory undergraduate partial derivatives. The study employed qualitative research and targeted students enrolled in Calculus 2. The research instrument used in collecting the data was lesson plans of partial derivatives as adapted from Dubinsky & McDonald (2001), as well as field notes, semi-structured interview forms, and reflections on learning. The results of the study revealed Understanding of learners while solving the following classroom can be searched by ignoring the process of acquisition for the partial demonstration that the student understands. The action is that the students can confirm their understanding. They understand the procedures and solve the problem of understanding. The action on the idea of making calculations as many times until you understand predict the outcome of the making process and can create new batches of feed. It was shown that the learners had an understanding of the process level. In group discussion issues about the functions learned in Calculus 1, the concepts of function matter were connected to make it easier for the level of understanding concerning the process and related objects, together with creating a structure of knowledge (Schema).