Length and area: Key characters in the curriculum story

Mathematics teachers often have questions about perimeter and area: should you teach them together or separately initially? What tasks should be included and how should they be sequenced? What order should different shapes appear? When should we worry about units? I had considered these issues as a teacher, but in developing the LUMEN curriculum, I had an opportunity to look with fresh eyes at how the story might unfold. I found it helpful to think of the central characters as being length and area rather than perimeter and area. In this article, I explore how those central characters might develop. [...]