Sidney Krimsky tutored high school math students during high school. He graduated from CCNY with a degree in engineering physics. He tutored high school math part-time during the 1960’s as a volunteer while working full time as an engineer. After retirement he joined the RE-SEED Program managed by the College of Education at Northeastern University in Boston in which about 90 STEM retirees volunteered one day per week to assist teachers and students within the Boston Public Schools. After three years he moved to West Hempstead and tried unsuccessfully to bring the RE-SEED model to public and private schools in New York State. He was hired by the Huntington Learning Center to teach high school math and science. During all that tutoring time he identified math that is not taught to high school students which is the subject of this book.