# Lesson 12

Partition Rectangles into Squares

### Lesson Purpose

The purpose of this lesson is for students to partition rectangles into equal-size squares.

### Lesson Narrative

Students have arranged tiles to make arrays and rectangles, represented their rectangles by shading squares on a grid, and completed the partitioning of rectangles into equal-size squares. In this lesson, students partition rectangles into equal-size squares with and without guiding marks and represent the total number of squares within the rectangles with equations that show the sum of the number of squares in each row or the number of squares in each column. Monitor for the ways students use what they know about the structure of arrays to plan and partition their rectangles. It is not important that students partition the rectangles into exactly equal-size squares.

- Action and Expression

- MLR2

### Learning Goals

Teacher Facing

- Partition rectangles into rows and columns of equal-size squares, and count to find the total number of squares.

### Student Facing

- Let’s partition rectangles into squares.

### Required Materials

Materials to Gather

### Required Preparation

### Lesson Timeline

Warm-up | 10 min |

Activity 1 | 15 min |

Activity 2 | 20 min |

Lesson Synthesis | 10 min |

Cool-down | 5 min |

### Teacher Reflection Questions

How did the work of arranging objects to make arrays support the understanding of partitioning rectangles into equal-size squares? What additional support is needed as students build this understanding?

### Suggested Centers

- Write Numbers (1–2), Stage 4: Skip Count by 2, 5, and 10 (Addressing)
- Target Numbers (1–5), Stage 7: Subtract Hundreds, Tens, or Ones (Supporting)