Unit Plan 34 (Grade 3 Math): Geometry Deep Dive—Attribute Hierarchies

Focus: Use precise geometry language to sort/classify quadrilaterals, build attribute hierarchies, and defend always/sometimes/never claims with examples and counterexamples.

Grade Level: 3

Subject Area: Mathematics (Geometry)

Total Unit Duration: 5 sessions (one week), 45–60 minutes per session

I. Introduction

Students investigate attributes of quadrilaterals (e.g., parallel/perpendicular lines, equal sides, right angles) and organize shapes into hierarchies (families and subcategories). They craft and test always/sometimes/never statements (e.g., “All squares are rectangles”) and justify conclusions with precise language and diagrams.

Essential Questions

• Which attributes determine a shape’s category and subcategory?
• How can a hierarchy help explain why some shapes fit in more than one category?
• What counts as evidence when defending an always/sometimes/never claim?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Describe and sort quadrilaterals using attributes (number of sides, parallel/perpendicular lines, equal sides, right angles).
2. Build and interpret an attribute hierarchy to show categories/subcategories (e.g., quadrilateral → parallelogram → rectangle → square).
3. Formulate and evaluate always/sometimes/never claims with counterexamples and precise vocabulary.
4. Communicate reasoning with labeled diagrams, clear definitions, and attention to precision (MP.6).

Standards Alignment — CCSS Grade 3

• 3.G.1: Understand that shapes in different categories (e.g., rhombuses, rectangles, squares) may share attributes; shared attributes can define a larger category (e.g., quadrilaterals). Recognize examples and draw non-examples.
• Mathematical Practices: MP.3 (Construct viable arguments & critique reasoning), MP.6 (Attend to precision).

Success Criteria — Student Language

• I can identify attributes (e.g., parallel lines, right angles) and use them to classify a shape.
• I can place shapes correctly in a hierarchy and explain my choice.
• I can defend an always/sometimes/never claim and give a counterexample if needed.
• I can label diagrams and use precise vocabulary so others understand my reasoning.