Gary has been an educator for over forty years and has taught every level from pre-school to graduate school.

After graduating from the University of Pittsburgh with a B.S. in early childhood education, he started and directed a pre-school center for his church that served the needs of its West Philadelphia community for thirty-nine years. He went on to earn a certification in secondary mathematics from Temple University and an M.Ed. in secondary mathematics from Arcadia University.

In 1988 Gary became a middle school mathematics teacher for the School District of Philadelphia. During his time working in Philadelphia, Gary served as a mathematics specialist, site director for the QUASAR Project, site director for Project FIRST, staff developer for family math, and as an urban systemic initiative professional development leader. He was also an adjunct professor of mathematics education at Arcadia University, the University of Pennsylvania, and Widener University. Gary was also the 1992 Teacher of Excellence Award winner for the Southwest Region in Philadelphia and one of the Pennsylvania winners for the NSF Presidential Award for Excellence in Mathematics Teaching.

Gary has conducted many seminars and workshops over his career. He has been a speaker at many NCTM National and Regional Conferences as well as local teacher conferences. He was a member of the NAEP Expert Panel on Mathematics Achievement Levels and a coauthor for the book Investigating Mathematics with PentaBlocks. Gary spent the last eighteen years of his career doing one of the best jobs he ever had: teaching high school students in Lower Merion School District. In 2017 he retired to do the best job he has ever had: reading books to his great-grandchild.