This study was designed to analyze the procedural fluency and written-mathematical explanation to select constructed response tasks of students in Thermodynamics problems. The study made use of 2 sections, composed of 26 students, in University Physics 1 to conclude on the research problem. It made use of the assumption that mathematical and English abilities control the students’ performance to problem solving. | Journal of Technology and Science Education THE STUDENTS’ PROCEDURAL FLUENCY AND WRITTEN-MATHEMATICAL EXPLANATION ON CONSTRUCTED RESPONSE TASKS IN PHYSICS Romiro G. Bautista Natural Sciences and Mathematics Department AMA International University (Bahrain) Received December 2012 Accepted January 2013 Abstract This study was designed to analyze the procedural fluency and written-mathematical explanation to select constructed response tasks of students in Thermodynamics problems. The study made use of 2 sections, composed of 26 students, in University Physics 1 to conclude on the research problem. It made use of the assumption that mathematical and English abilities control the students’ performance to problem solving. Using Pearson-r and One-way ANOVA, it was found out that their procedural fluency on constructed response tasks is significantly related to their written-mathematical explanation ability, and a significant difference on their performance when grouped according to their mathematical and English ability. Bonferroni Correction Post Hoc Test results confirmed the assumptions of the study: the students’ procedural fluency is dependent to their mathematical ability, both algebraic and trigonometric, while their written-mathematical explanation is associated to their English ability. Keywords – Mathematical Procedural Fluency, Written-Mathematical Explanation, Constructed Response Tasks, Problem Solving. ---------- 1 INTRODUCTION Problem solving in Physics, as influenced by mathematical learning theories, is mystified as difficult over the years as students hold negative stereotype images towards the subject (Wambagu & Changeiywo, 2006; Bautista, 2012a). These stereotypical tendencies had hampered its efficacy over the years and became a concomitant factor to be addressed properly. This calls for a sound technique of decontextualized set of skills on convergent reasoning in engaging students to higher cognition activities towards