Lesson 8

Formas de encontrar la longitud desconocida (parte 2)

Lesson Purpose

The purpose of this lesson is for students to use the attributes of two-dimensional figures (such as perimeter and symmetry) to reason about side lengths.

Lesson Narrative

In the previous lesson, students used given side lengths and symmetry to find the perimeter of a figure. In this lesson, students reason in the other direction—given the perimeter and information about symmetry, they find the side lengths of two-dimensional figures. Students also practice completing a figure given a line of symmetry and half of the figure, and then reason about the perimeter of the whole figure. Along the way, students reinforce their ability to add fractions and to multiply fractions by whole numbers.

  • Engagement
  • MLR8

Activity 2: El diseño de Lin

Learning Goals

Teacher Facing

  • Find the unknown side lengths of two-dimensional shapes using their attributes.

Student Facing

  • Encontremos las longitudes desconocidas en figuras.

Required Materials

Materials to Gather

Required Preparation

CCSS Standards

Lesson Timeline

Warm-up 10 min
Activity 1 20 min
Activity 2 15 min
Lesson Synthesis 10 min
Cool-down 5 min

Teacher Reflection Questions

The tasks in this lesson prompted students to apply what they learned about adding fractions and multiplying fractions by a whole number. How comfortable were students with these operations? What ideas or strategies do students need more practice with?

Suggested Centers

  • Which One? (K–5), Stage 5: Grade 4 Shapes (Addressing)
  • Can You Draw It? (1–5), Stage 5: Grade 4 Shapes (Addressing)
  • Compare (1–5), Stage 5: Fractions (Supporting)
  • Compare (1–5), Stage 7: Multi-digit Operations (Supporting)

Print Formatted Materials

Teachers with a valid work email address can click here to register or sign in for free access to Cool Down, Teacher Guide, and PowerPoint materials.

Student Task Statements pdf docx
Lesson Cover Page pdf docx
Cool Down Log In
Teacher Guide Log In
Teacher Presentation Materials pdf docx