Communicating reasoning and constructing models fold nicely into a geometry activity involving the building of nesting boxes.
Bird Boxes Build Content Area Knowledge
Sherri Ann Cianca
Capturing Thinking on the Talk Frame
Tutita M. Casa
This instructional tool helps students engage in discussions that foster student reasoning, then settle on correct mathematics.
Informing Practice: Examples as Tools for Constructing Justifications
research matters for teachers
Kristen N. Bieda and Jerilynn Lepak
Research explores how to help students build from, instead of building with, examples when justifying mathematical ideas.