Main Article Content
The purposes of this study were: 1) to study Mathayomsuksa III students’ conceptual knowledge on circle after being taught through the conjecturing and proving method with GeoGebra program; and 2) to study Mathayomsuksa III students’ proof abilities on circle after being taught through conjecturing and proving method with GeoGebra program. The sample group was 40 Mathayomsuksa III students of Prasarnmit Demonstration School (Secondary), in the second semester of 2018 academic year. The research instruments of this study were: 1) 6 lesson plans that allowed students to learn the topic via conjecturing and proving method with GeoGebra program; and 2) The conceptual knowledge and proof abilities test on the topic of circle.
The research findings revealed that: 1) after being taught by conjecturing and proving method with GeoGebra program, over 60% of the sample group had conceptual knowledge on circle score that satisfied the criteria at a significant level of .05; and 2) after being taught by conjecturing and proving method with GeoGebra program, over 60% of the sample group had proof abilities on circle score that satisfied the criteria at a significant level of .05.
"The opinions and contents including the words in papers are responsibility by the authors."
"ข้อคิดเห็น เนื้อหา รวมทั้งการใช้ภาษาในบทความถือเป็นความรับผิดชอบของผู้เขียน"
 Sherard III, W. H. 1981. Why is Geometry a Basic Skill? The Mathematics Teacher, 74(1), p. 19-21.
 The Ministry of Education. 2008. The Basic Education Core Curriculum. Bangkok: The Agricultural Co-operative Federation of Thailand.
 The Institute for the Promotion of Teaching Science and Technology. 2011. Additional Mathematics 2nd Semester for Secondary 3. Bangkok: Business Organization of the Office of the Welfare Promotion Commission for Teachers and Educational Personnel.
 Trairong Klumbut. 2014. The Development of Activity Packages to Enhannce Reasoning Ability on Reasoning about Triangle and Quadrilateral for Grade 9 Students. Master of Education (Science Education), Naresuan University.
 Saranluck Butrarat. 2010. Learning Activites Management to Promote Students’ Reasoning Skill on “Circle” by Using The Geometer’s Sketchpad Program for Matthayomsuksa Three Students at Banglamung School. Master of Education (Teaching Mathematics), Kasetsart University.
 Supattra Kerdmongkon. 2007. Learning Activities on Geometric Circle Properties Using Dynamic Geometry Software for Mathayomsuksa III Students. Master of Education (Mathematics), Srinakharinwirot University.
 Morselli, F. 2006. Use of Examples in Conjecturing and Proving: An Exploratory Study. In Novotna, J., et al. (Eds.). Proceedings of 30th Conference of the International Group for the Psychology of Mathematics Education. p. 185-192. Prague: Atelier Guimaec.
 Alibert, D. and M. Thomas. 2002. Research on Mathematical Proof. In David, T. (Ed.). Advanced Mathematical Thinking. p. 215-230. New York: Kluwer Academic Publishers.
 Ubol Klongkratoke. 2012. Surveying Geometry Using Technology. In Preecha Naoyenphon, et al. (Eds.). Provision of Learning Experience in Mathematics. p. 1-119. Nonthaburi: Sukhothai Thammathirat Open University.
 Frank, A. B. and Mariotti, M. A. 2010. Conjecturing and Proving in Dynamic Geometry: The Elaboration Of Some Research Hypotheses. In Guerrier, V. D., et al. (Eds.). Proceedings of CERME 6. p. 231-240. Lyon: INRP.
 Preiner, J. 2008. Introducing Dynamic Mathematics Software to Mathematics Teachers: the Case of GeoGebra. Salzburg. University of Salzburg. Retrieved March 26, 2018, from https://archive.geogebra.org/static/publications/jpreiner-dissertation.pdf
 Arends, R. L. 2012. Learning to Teach. 9th ed. New York: McGraw-Hill.
 Aumporn Makanong. 2015. Mathematics for Secondary School Teachers. 2nd ed. Bangkok: Faculty of Education Chulalongkorn University.
 Frerking, B. G. 1994. Conjecturing and Proof Writing in Dynamic Geometry. Doctor of Philosophy (Mathematics Education), Georgia State University.
 Nguyen, D. N. 2012. The Development of the Proving Process Within a Dynamic Geometry Environment. European Researcher, 32(10-2), p. 1731-1744.
 Hoyles, C. and Jones, K. 1998. Proof in dynamic geometry contexts. In Mammana, C. and Villani, V. (Eds.). Perspectives on the Teaching of Geometry for the 21st-Century. p. 121-128. Dordrecht: Kluwer.
 Goddjin, A., Kindt, M. and Reuter, W. 2014. Geometry with Applications and Proofs: Advanced Geometry for Senior High School, Student Text and Background Information. Rotterdam: Sense Publishers.
 Hanna, G. 2002. Mathematical Proof. In Tall, D. (Ed.). Advanced Mathematical Thinking. p. 54-64. New York: Kluwer Academic.