Talks, seminars, workshops, and invited participation in conferences.
-- Mathematics and History of Mathematics:

“Allowing Unexpected: Creativity in Your Classroom”, (4 talks) University of Cape Town, Stellenbosch University, CASME (Durban), AMESA, February, 2014.

“Allowing Unexpected: Creativity in Your Classroom”, keynote speaker 62nd Western Illinois Teachers Conference, Macomb, IL, March 2013.

“Points of Intersection”, Gathering for Gardner 10, Atlanta, GA, March 2012.

“Adventures in non-Euclidean Geometry”, Robert Noyce Teacher Scholarship Program Conference Building Excellence in STEM Teaching, Washington DC, July 2, 2009.

"Geometry and motion links mathematics and engineering in collections of 19th century kinematic models and their digital representation", ICMI Centennial Anniversary Symposium, Rome, Italy, March 5-8, 2008.

“Exploring the hyperbolic plane through crochet”, Coxeter Symposium, Princeton University, November 3, 2006.

“Exploring the hyperbolic plane through crochet”, Gathering for Gardner 7 (by invitation only), Atlanta, GA, March 2006.

“Exploring the hyperbolic plane through crochet”, AMS Special Session on Mathematics and Mathematics Education in Fiber Arts, Joint Mathematical Meetings, Atlanta, GA, January 2005.

“History of Mathematics and Mechanics in Digital Reuleaux Kinematic Mechanism Collection”, ICME-10, July 2004, Copenhagen, Denmark.

“Using a Digital Kinematic Model Collection in the Classroom”, International Conference: Scientific Instrument Collections in Universities, Dartmouth, NH, June 26-29, 2004.

(by invitation only) “Mathematical Aspects of Franz Reuleaux Kinematic Model Collection”, AMS Special Session on History of Mathematics, AMS Sectional Meeting, New York, April 13th, 2003.

(by invitation only) “How it was to study and to teach mathematics in Cornell at the end of 19th century?” AMS Special Session in History of Mathematics, Joint Mathematical Meetings, January 18, 2003, Baltimore, MD.

Invited plenary address. “Mathematical Way of Thinking – When is it Creative?” International Conference on Teaching Gifted Students and Increasing Creativity in Mathematics Education, Riga, Latvia. July 15-18, 2002.

“The Role of Physical Models in Teaching Hyperbolic Geometry”, Janos Bolyai Conference on Hyperbolic Geometry, Hungarian Academy of Sciences, Budapest, Hungary, 8-12 July, 2002

“History Makes Mathematics Alive”, Mathematics Education and History Contributed Paper Session at the AMS-MAA Joint Meeting, Washington, DC, USA, January 19-22, 2000.

(by invitation only) “Mathematics in Latvia Through Centuries”, AMS Special Session on The History of Mathematics, AMS-MAA Joint Meeting, Washington, DC, USA, January 19-22, 2000.

“The Role of Physical Models in Teaching Geometry”, Mathematics Education Contributed Paper Session at the AMS-MAA Joint Meeting, San Antonio, Texas, January 13-16, 1999, USA

(by invitation only) ICMI Study: Teaching Mathematics at the Undergraduate Level, Singapore, December 8-12, 1998.

International conference of mathematics educators from Nordic countries: Norma-98, Kristiansand (Norway), June 5-9, 1998.

(by invitation only) ICMI Study: The Role of the History of mathematics in the teaching and learning mathematics, Luminy (France), April 19-26, 1998.

Invited Plenary Address, 4th Annual New York Graduate Mathematics Education Research Conference, Syracuse University, October 25, 1997.

"Living geometry for liberal arts majors: hands-on and discovery-based approaches", MathFest-97, Atlanta, Georgia, USA, 1997.

Fourth International Seminar: From Misconceptions to constructed understanding, June 13-15, 1997, Cornell University. Ithaca, NY, USA

Co-organizer, International Conference Teaching Mathematics for 21st Century, July 1-4, 1996, Riga, Latvia.

(by invitation only) ICMI Study: Perspectives of the Teaching Geometry for 21st Century, Catania, Italy, September 1995.

"On teaching algorithmic methods to middle and high school students," International Congress of Mathematicians, Zurich, Switzerland, August 1994

“Teaching geometry through problems”, International Conference on Teaching High School Geometry, Stockholm, Sweden, May 8, 1994.

“Complexity Gaps of Turing Machines on infinite words”, International Conference: Foundations Of Theoretical Computer Science, Kazan, Russia, June, 1987