I retired in 2014 after teaching in private secondary boarding schools for 40 years, the last 31 at Phillips Academy in Andover, MA. I always enjoyed teaching! I discovered GeoGebra in January 2009 and am having fun learning its power. I received a Ph.D. in math from Northwestern University in 1978. My latest interest is learning about hyperreal--infinitesimals and infinitely large hyperreal numbers.