Vela, Melissa Jo2011-07-142011-08-242011-07-142011-08-242011-07-14January 20http://hdl.handle.net/10106/5883We report on a study of sixteen high school calculus and seven precalculus students' concept image and concept definition of continuity after one-trimester of instruction at a large suburban high school in the southwestern United States. The researchers developed a questionnaire based upon the work of Tall and Vinner (1981) to determine if calculus students had developed a more sophisticated concept image and concept definition of continuity than students in pre-calculus after a typical treatment in both courses. Using data from the written assessment it was not evident that calculus students demonstrated a more sophisticated concept image and concept definition than pre-calculus students. However, findings suggest that a weak concept image or concept definition of continuity reflects practices in precalculus and calculus instruction.enM.S.