This activity involves finding the distance between two points in a coordinate plane and emphasizes reasoning from repeated calculations, which is one of the mathematical practices specified by the Common Core State Standards for Mathematics.
Edited by Barbara Zorin, drbzorin@gmail.com, MATHBonesPro. Readers are encouraged to submit manuscripts through http://mtms.msubmit.net.
Ryota Matsuura, matsuura@stolaf.edu, is an assistant professor of mathematics at St. Olaf College in Northfield, Minnesota. His interests include how teachers acquire mathematical habits of mind and apply these habits to their classroom instruction.