Unit 7, Lesson 13
Encontremos medidas de ángulos
Grado 4
Preparation
Lesson Narrative
In this lesson, students use tactile tools to find angle measurements and observe more clearly that angles are additive. They compose and decompose angles by arranging paper cutouts, by folding paper or tracing, and by drawing diagrams. Students arrange smaller angles, the sizes of which are unknown, into larger angles with familiar sizes and features (, , and ). Once the measurement of an angle is known, they use it to find those of other angles. For example, if two copies of Angle X form a right angle, Angle X must be . If another angle, Z, can be decomposed into three of these angles, then Z must be .
Encourage students to continue to collect, define, and illustrate new terms to support communication and reasoning at the end of each lesson.
- Representation
None
- Explain (orally and in writing) strategies for determining the size of an angle, based on composing and decomposing angles.
- Compongamos y descompongamos ángulos para encontrar sus medidas.
Required Preparation
- Each group of 2–4 students needs one copy of the handout from the blackline master.
- Cut out the 4 copies of each angle (P, Q, R, and S) in advance, or prepare scissors and extra time for students to cut out the angles from the handout.
- If using patty paper instead of cutouts of the angles, each student needs 1–2 sheets of patty paper.
Teacher Reflection Questions
The work of finding angle measurements in this lesson offered opportunities to reason about equal groups. Did you hear students use this type of reasoning? What were some other ways students reasoned about the angle sizes?