I"m a retired math professor. My principal mathematical interest is the topology of dynamical systems. For over twenty-five years I used computers in teaching and, in particular, students’ doing programming in APL, J, and Mathematica (in numerical analysis also Pascal, BASIC, and FORTRAN) in order to learn fundamental concepts and to visualize mathematical operations and phenomena. My computer experience began in 1959 with a course in assembly programming on the Univac I.