Current trends in middle school curricula highlight the importance of integrating algebraic reasoning throughout the middle grades. The use of innovative technologies offers one exciting way to engage students in algebraic problem-solving activities. In this article, we report on our efforts to design for seventh graders a computer-based instructional unit that would not only address state standards but, we hoped, also lay the groundwork for the students' subsequent formal study of algebra. The software we chose, SimCalc MathWorlds, is available free of charge via the World Wide Web at www.simcalc. umassd.edu. Look on the first page of this site. With this program, students can animate characters on the screen by creating graphs of position and velocity.