The Parent Plan explicitly lists the skill "Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category." The lesson asks students to sort shapes into categories (regular vs. irregular) in Activity 2 and to complete an online activity that uses Venn diagrams to sort polygons (Day 2), which has students place shapes into overlapping categories. The lesson also teaches and has students practice identifying congruent sides and angles, which supports comparing category attributes.

Students sort and classify quadrilaterals using properties like numbers of parallel sides, congruent sides, and right angles on the Quadrilateral Classification 1 and 2 activities. The Parent Plan and answer key explicitly prompt and model category relationships (e.g., asking "Is a square a rectangle or is a rectangle a square?" and stating "a square is a special kind of rectangle because it has 4 right angles..."). Activities (Getting Specific About Quadrilaterals and related questions) require students to write descriptions and explain how rectangles, parallelograms, rhombi, and squares relate to one another by shared attributes.

The Parent Plan explicitly lists "Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category" as a skill to be learned. Students complete classification and identification tasks: they match shapes with names (e.g., rhombus, equilateral triangle, regular hexagon), label sides/angles/vertices, and answer true/false items about congruent sides and congruent angles. Review and test pages ask students to identify and classify quadrilaterals and triangles and to determine properties of given shapes.

The lesson's Skills list explicitly states students will "Understand that attributes belonging to a category of two-dimensional figures also belong to all subcategories of that category." Students are directed to identify and classify quadrilaterals and triangles, and to include specific geometry information when creating ABC pages. A sample page illustrates a right triangle and labels its right angle, giving an example of an attribute tied to a category of shapes.

The lesson explicitly states "Remember that a square is a type of rectangle" and uses that idea to explain that square faces may serve as bases of a rectangular prism and that a cube is a rectangular prism because its faces are squares. Students match and label shapes (rectangular prism, cube, triangular prism, etc.) on the activity page, which requires recognizing category membership of 2D-base shapes. The parent prompts ask students to identify bases and note that a prism is named for the shape of its bases, linking 2D polygon types to 3D prism names.