Julie S. Long, firstname.lastname@example.org, teaches mathematics education at the University of Alberta in Edmonton, Alberta, Canada. She enjoys listening to elementary school students talk about their understanding of math. E-mail your insights into a student's mathematical thinking to email@example.com. Include “back talk” in the subject line. See detailed guidelines for submissions at www.nctm.org/tcmdepartments. This “back talk” dialogue is taken from a larger study: Long, Julie S. “A Study of Elementary Students' Concepts and Skills in Area Measurement.” Master's thesis, University of New Brunswick, Fredericton, NB, 2004.