Ways to Find Angle Measurements
10 min
Narrative
This Warm-up encourages students to look for and make use of structure in an image to identify the lines of symmetry it has (MP7). Students could try to find all the segments or angles that are the same size as a way to identify lines of symmetry, but keeping track of all the pieces can be rather impractical. Instead, students could pay attention to the composition of the image— a five-sided figure on the outside and a five-point star on the inside, where all of the five parts are the same—and use that insight to determine the number of lines of symmetry.
Launch
- Groups of 2
- “How many do you see? How do you see them?”
- Display the image.
- 1 minute: quiet think time
Teacher Instructions
- Display the image.
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Record responses.
Student Task
How many lines of symmetry do you see? How do you see them?
Sample Response
Sample responses:
- The pentagon has 5 corners. A line of symmetry goes through each corner.
- The pentagon has 5 equal sides. A line of symmetry goes through each side.
- The star has 5 points. A line of symmetry goes through each point.
Activity Synthesis (Teacher Notes)
- Invite students to share how they identified the lines of symmetry. Display the original image for students to mark up and use in their explanation.
- Some students may have double-counted and say that there are 10 lines of symmetry. Invite others to respond to that claim.
- Consider asking:
- “Who can restate the way _____ saw the lines of symmetry in different words?”
- “Did anyone see the lines of symmetry the same way but would explain it differently?”
- “Does anyone want to add an observation to the way _____ saw the lines of symmetry?”
Standards
- 4.G.3·Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
- 4.G.A.3·Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
25 min
15 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Ways to Find Angle Measurements
10 min
Narrative
This Warm-up encourages students to look for and make use of structure in an image to identify the lines of symmetry it has (MP7). Students could try to find all the segments or angles that are the same size as a way to identify lines of symmetry, but keeping track of all the pieces can be rather impractical. Instead, students could pay attention to the composition of the image— a five-sided figure on the outside and a five-point star on the inside, where all of the five parts are the same—and use that insight to determine the number of lines of symmetry.
Launch
- Groups of 2
- “How many do you see? How do you see them?”
- Display the image.
- 1 minute: quiet think time
Teacher Instructions
- Display the image.
- “Discuss your thinking with your partner.”
- 1 minute: partner discussion
- Record responses.
Student Task
How many lines of symmetry do you see? How do you see them?
Sample Response
Sample responses:
- The pentagon has 5 corners. A line of symmetry goes through each corner.
- The pentagon has 5 equal sides. A line of symmetry goes through each side.
- The star has 5 points. A line of symmetry goes through each point.
Activity Synthesis (Teacher Notes)
- Invite students to share how they identified the lines of symmetry. Display the original image for students to mark up and use in their explanation.
- Some students may have double-counted and say that there are 10 lines of symmetry. Invite others to respond to that claim.
- Consider asking:
- “Who can restate the way _____ saw the lines of symmetry in different words?”
- “Did anyone see the lines of symmetry the same way but would explain it differently?”
- “Does anyone want to add an observation to the way _____ saw the lines of symmetry?”
Standards
- 4.G.3·Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.
- 4.G.A.3·Recognize a line of symmetry for a two-dimensional figure as a line across the figure such that the figure can be folded along the line into matching parts. Identify line-symmetric figures and draw lines of symmetry.