Research findings show that teachers often need considerable help developing conceptual understanding of geometric definitions (Borasi 1996).
Randall Groth is interested in using students' mathematical thinking to improve instruction.
Edited by Fran Arbaugh, email@example.com, and John Lannin, LanninJ@missouri.edu, members of the mathematics education faculty at the University of Missouri—Columbia, Columbia, MO 65203. This department serves as a forum for the exchange of ideas and a source of activities and pedagogical strategies for teacher educators in their day-to-day work with prospective and practicing teachers. Readers are encouraged to send manuscripts appropriate for this section by accessing tcm.msubmit.net.