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Acute Angle Explorer

Run the Acute Angle Explorer MicroSim Fullscreen

Place the following line in your website to include this MicroSim in your course:

<iframe src="https://dmccreary.github.io/geometry-course/sims/acute-angle-explorer/main.html" height="502px" scrolling="no"></iframe>

Description

This MicroSim allows students to explore how angles are classified based on their measure. A canvas-based slider adjusts the angle from 1 to 180 degrees. Two rays meet at a central vertex: a fixed horizontal ray in dark blue and a rotating ray in bright red. The angle arc is drawn in green, and the vertex is highlighted with an orange circle. As students drag the slider, the angle measure updates in real time and the classification text changes color to indicate whether the angle is acute (green), right (blue), obtuse (orange), or straight (purple).

How to Use

  1. Drag the slider at the bottom of the canvas to change the angle measure
  2. Observe the two rays and the angle arc as the angle changes
  3. Read the classification text below the slider to see if the angle is acute, right, obtuse, or straight
  4. Notice the color coding that reinforces each angle type

Lesson Plan

Learning Objective

Students will identify acute angles and understand their range of measures (Bloom's Level: Understanding).

Warm-Up (5 minutes)

Ask students: "What does the word 'acute' mean in everyday English?" Connect the idea of "sharp" to angles that are narrow and less than 90 degrees.

Guided Exploration (10 minutes)

  1. Open the MicroSim and set the angle to 45 degrees (the default)
  2. Ask students to predict: "Is this angle acute, right, or obtuse?"
  3. Slowly drag the slider toward 90 degrees and ask: "At what point does the classification change?"
  4. Continue past 90 degrees and observe the obtuse classification
  5. Discuss: "What is special about exactly 90 degrees?"

Independent Practice (5 minutes)

Have students answer:

  • What is the range of acute angle measures? (1 to 89 degrees)
  • What is the range of obtuse angle measures? (91 to 179 degrees)
  • What angle measure is exactly a right angle? (90 degrees)
  • What angle measure is a straight angle? (180 degrees)

Assessment

Students should be able to classify any given angle measure without the MicroSim, demonstrating that they have internalized the boundaries between angle types.

References

Note: Remember to take a screenshot of this MicroSim and save it as acute-angle-explorer.png in this directory for social media previews.