Technology has become an indispensable aspect of most mathematics education. This is a full-color textbook, abundant with graphics, algorithms, and assignments, that both introduces Sage, a free, open-source computer algebra system, and reinforces important mathematical ideas of undergraduate mathematics, including some that a transitioning student will not yet have seen. This book should be useful for any situation where an individual is moving from "high school" mathematics, in which we include basic calculus, to "university" mathematics, which includes intermediate calculus and a lot of stuff besides, and is willing to experiment with a computer.