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Angle Builder

Run the Angle Builder MicroSim Fullscreen
Edit in the p5.js Editor

About This MicroSim

The Angle Builder is an interactive tool that allows students to create and explore angles by rotating a ray around a fixed vertex. As the angle changes, students can observe:

  • Angle measurement in degrees (0° to 360°)
  • Angle classification (acute, right, obtuse, straight, reflex)
  • Complementary angles (two angles that sum to 90°)
  • Supplementary angles (two angles that sum to 180°)

How to Use

  1. Slider: Drag the slider to rotate Ray 2 and create different angles
  2. Reset: Click "Reset to 0°" to return to the starting position
  3. Random: Click "Random" to generate a random angle
  4. Snap: Use the dropdown to snap to common angle measures (15°, 30°, 45°, 90°)

Angle Classifications

Angle Type Measure Color
Acute 0° < angle < 90° Green
Right angle = 90° Purple
Obtuse 90° < angle < 180° Orange
Straight angle = 180° Red
Reflex 180° < angle < 360° Blue

Learning Objectives

After using this MicroSim, students will be able to:

  • Create angles of specific measures using ray rotation
  • Classify angles as acute, right, obtuse, straight, or reflex
  • Calculate complementary and supplementary angles
  • Analyze the relationship between ray positions and angle measurements

Bloom's Taxonomy Level

Creating and Analyzing - Students actively construct angles and analyze the relationships between angle measures and classifications.

Iframe Embed Code

<iframe src="https://dmccreary.github.io/geometry-course/sims/angle-builder/main.html"
        height="602px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Grade Level

9-12 (High School Geometry)

Duration

15-20 minutes

Prerequisites

  • Understanding of rays and vertices
  • Basic knowledge of degree measurement

Activities

  1. Exploration (5 min): Have students freely explore the angle builder, creating various angles and observing the classifications.

  2. Targeted Practice (5 min): Ask students to create specific angles:

  3. A 45° acute angle
  4. A 90° right angle
  5. A 120° obtuse angle

  6. A 180° straight angle

  7. Complementary Challenge (3 min): For any acute angle created, have students verify that the complement shown equals 90° minus their angle.

  8. Supplementary Challenge (3 min): For angles less than 180°, verify that the supplement shown equals 180° minus their angle.

  9. Classification Game (4 min): One student calls out an angle type, and another must create an angle of that type using the slider.

Assessment

  • Can students create angles of specified measures?
  • Can students correctly classify angles by type?
  • Can students calculate complementary and supplementary angles?

References

  1. Angles and Their Measures - Khan Academy - Introduction to angles
  2. Types of Angles - Math is Fun - Comprehensive angle guide