Teachers who have been in the classroom for a while know that year after year we see students make the same mistakes that previous students made. To prevent these errors, we try a variety of techniques, but it seems that no matter what we do, they reappear in students' work time and time again. Are we, despite our best efforts, contributing to these mistakes? I believe that we do, indeed, use some practices that inadvertently undermine our best intentions.
Robin S. Kalder, firstname.lastname@example.org, taught secondary school mathematics for many years and is an associate professor of mathematics education at Central Connecticut State University in New Britain. Her research areas are mathematics education, technology in the classroom, and preservice teachers' attitudes toward mathematics.