Lesson 10
Rectas perpendiculares y medidas de ángulos
Lesson Purpose
Lesson Narrative
In a previous lesson, students learned that a 1-degree angle measures a turn through \(\frac{1}{360}\) of a circle and that a protractor could be used to measure angles in degrees.
In this lesson, students practice using a protractor to measure a variety of angles—angles formed by rays or line segments and those that are in other two-dimensional figures. Students consider how to position the tool, which set of numbers to use, and whether their measurements make sense.
Next, students are prompted to fold paper to create two lines that form right angles. They learn that intersecting lines that form \(90^\circ\) angles are perpendicular. They then practice identifying perpendicular lines and segments.
- Representation
- MLR8
Learning Goals
Teacher Facing
- Recognize that perpendicular lines meet or cross at a right angle.
- Use a protractor to measure angles.
Student Facing
- Midamos todo tipo de ángulos.
Required Materials
Materials to Gather
Required Preparation
Activity 2:
- Prepare at least 2 pieces of paper (or sticky notes) for each student.
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
Suggested Centers
- Target Measurements (2–5), Stage 4: Degrees (Addressing)
- Compare (1–5), Stage 5: Fractions (Supporting)