I am working on a 3rd grade unit that encompasses area, perimeter, and Geometry.
We are hoping to get our students to be able to sort shapes according to defining and non-defining attributes using a graphic organizer that illustrates hierarchical inclusion.
I am struggling with finding a consistent definition of “shape”
Is a shape, by definition, a closed figure? Or is “closed” defining when a figure is 2D or 3D?
Am I correct that being closed is a defining attribute of plane figures?