# Lesson 17

Más problemas sobre perímetros

### Lesson Purpose

The purpose of this lesson is for students to solve geometric problems using their understanding of length measurements, unit conversion, multiplicative comparison, and addition or subtraction of fractions.

### Lesson Narrative

In a previous lesson, students were reminded about the relationship between the side lengths and the perimeter of a rectangle and reasoned multiplicatively to solve problems about those measurements. In this lesson, they continue to do so but in contexts that require them to convert the units and interpret them. Students also consider the perimeter of other quadrilaterals.

• Representation
• MLR7

### Learning Goals

Teacher Facing

• Solve problems involving perimeter using multiplicative comparison and addition or subtraction of fractions (including mixed numbers)

### Student Facing

• Resolvamos problemas sobre el perímetro de varias figuras.

### Required Materials

Materials to Copy

• Missing Measurements - Large, Spanish
• Missing Measurements - Small, Spanish

### Required Preparation

Activity 2:

• If the activity is done as a gallery walk, print and cut 1–2 copies of the blackline master with the larger images and post them around the classroom. Otherwise, print and cut 1 copy of the blackline master with the smaller images for each group of 3–4 students.

Building On

### 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

As students shared their ideas today, how did you ensure all students’ voices were heard? In what ways did you show that all voices are valued and important for collective learning?

### Suggested Centers

• Can You Draw It? (1–5), Stage 4: Area and Perimeter (Supporting)
• Rectangle Rumble (3–5), Stage 3: Factors 1–10 (Supporting)