Assessing the Learning of Proofs in High School Terra Stout, Texas State Technical College, Abilene, TX, USA Jerry Dwyer (jerry.dwyer@ttu.edu), Robert Byerly, Texas Tech University Lubbock, TX, USA Jennifer Wilhelm, University of Kentucky, Lexington, KY, USA Abstract: Proofs were introduced to high school students by a college mathematician. Student interest and knowledge level were assessed through pre and post tests. There was a significant gain in student knowledge but not in interest. Student learning of proof concepts was clearly displayed, while common errors were often related to lack of algebra skills. Student understanding of the meaning of proof was enhanced and this enhancement is discussed in the context of several existing theories of learning proofs. Introduction Proofs are an integral part of mathematics, however proof writing has declined at the high school level in the United States. Therefore, students are not prepared for proofs in college mathematics courses. This may lead students to believe that proofs are both difficult and relatively unimportant. The main goal of this study was to introduce proofs to high school students in such a way that they would both understand and appreciate the importance of their role in mathematics. Students‟ interest in mathematics and their awareness of the importance of mathematics in future coursework was also studied. Students were given a pretest and a posttest in order to assess student improvement in the area of proofs. They were also given an interest inventory survey to assess any changes in interest in mathematics and more specifically proofs during the course of this study. Researchers presented lessons once a week for approximately twenty to thirty minutes during the course of this study. The students were presented with outlines for note taking at the beginning of each lesson and were presented with short homework assignments for practice at the conclusion of each lesson. The lessons began with logic and truth values, continued with the basics of proof, and finally touched on set theory. While the lessons were mainly presented as lectures, the students were encouraged to ask and answer questions during the lessons. Due to the small number of students, statistical results are limited. Instead individual problems and solutions from the tests were analyzed to gain a better understanding of the extent of student improvement in the area of proof. Student interest was also more closely examined during interviews given at the conclusion of the study. The study described in this paper was primarily intended to assess student gains in proof writing ability. However we also study students‟ written and interview responses in the context of the theories described in the literature review below. The setting for the study is a high school in the United States. However the implications and findings are closely related to proof writing in other countries such as the United Kingdom and Japan.