A famous mathematics educator from Africa*

USA but worked all over the world, in all continents. His social concerns and intellectual development as well as his research into mathematics, mathematics education, linguistics, and psychology began in Africa, a continent to which he made several significant contributions. He was eighth of nine children, had to work for his living from an early age, but always sought to learn and become educated. He committed himself to study, read whatever came his way, particularly mathematics texts, and often earned money by tutoring others. In 1929, at the age of 18, he earned a bachelor of science degree. Between the ages of 20 and 25, studying on his own, he took external examinations in Cairo and obtained teaching licenses in chemistry and physics (1931), in mathematics (1932), and an advanced studies diploma in mathematics in (1936), all from the University of Marseilles, France. He was a self-taught mathematician whose independent studies led him to from the and a doctorate in 1937 from Basle University, in Switzerland (thesis title: Les cas essentiellement géodésiques des équations de Hamilton-Jacobi intégrables par séparation des variables1). * I am grateful to Marilyn Frankenstein, Shakti Gattegno, Paulus Gerdes, Dick Tahta, and David Wheeler for their critical review of an earlier version