Unit Plan 5 (Grade 2 Math): Rectangular Arrays—Equal Groups as Repeated Addition

Focus: Build and count rectangular arrays up to 5×5; write repeated addition equations as equal addends; connect to area tiles informally.

Grade Level: 2

Subject Area: Mathematics (Operations & Algebraic Thinking)

Total Unit Duration: 5 sessions (one week), 35–45 minutes per session

I. Introduction

This week, students use equal groups arranged in rows and columns to make arrays and count items efficiently. They match each array to a repeated addition equation with equal addends and explain their choices with short because statements. We preview the idea of covering shapes with tiles (informal area) without formal formulas.

Essential Questions

• How does a rectangular array show equal groups?
• How do I write a repeated addition equation that matches my array?
• Which counting strategy (row-by-row, column-by-column, skip-count) is most efficient and why?

II. Objectives and Standards

Learning Objectives — Students will be able to:

1. Build and label arrays (up to 5×5) with clear rows and columns.
2. Write repeated addition equations using equal addends to represent an array’s total.
3. Use structure (same-size rows/columns, skip-count by 2s/5s) to check reasonableness.
4. Explain thinking with a because statement linked to a matching model.
5. Connect arrays to tiles that cover space (informal area idea).

Standards Alignment — CCSS Grade 2 (spiral across the unit)

• 2.OA.4: Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and 5 columns; write an equation to express the total as a sum of equal addends.
• Mathematical Practices: MP.2 (Reason abstractly & quantitatively) and MP.8 (Look for & express regularity in repeated reasoning) emphasized; MP.6 precision in labeling.

Success Criteria — Student Language

• I can make a ___ by ___ array and label the rows and columns.
• I can write a repeated addition equation with equal addends that matches my array.
• I can skip-count or add row totals to find the total, and explain because my model shows equal groups.