Unit 8, Lesson 8
Formas de encontrar la longitud desconocida (parte 2)
Grado 4
Preparation
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
- Explain (orally) strategies for determining an unknown side length for a two-dimensional figure given the perimeter and lines of symmetry.
- Encontremos las longitudes desconocidas en figuras.
Required Materials
Activity 1
Activity 2
Required Preparation
None
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?