This discussion of a new computer-based medium describes microcomputer (MC) painting and its principal tool, the MC paintbrush, and explores their potential roles in mathematics, computer science, and art education in secondary schools. This paper describes the school computer, discusses capabilities of MC painting, explains how MC painting is done and what the computer does, argues for classroom use of the school computer, and discusses the meaning of literacy in mathematics, computers, and art. (Author/JD)