Standard #: MA.3.GR.1.3


This document was generated on CPALMS - www.cpalms.org



Draw line(s) of symmetry in a two-dimensional figure and identify line-symmetric two-dimensional figures.


Clarifications


Clarification 1: Instruction develops the understanding that there could be no line of symmetry, exactly one line of symmetry or more than one line of symmetry.

Clarification 2: Instruction includes folding paper along a line of symmetry so that both halves match exactly to confirm line-symmetric figures.



General Information

Subject Area: Mathematics (B.E.S.T.)
Grade: 3
Strand: Geometric Reasoning
Standard: Describe and identify relationships between lines and classify quadrilaterals.
Date Adopted or Revised: 08/20
Status: State Board Approved

Benchmark Instructional Guide

Connecting Benchmarks/Horizontal Alignment

 

Terms from the K-12 Glossary

  • Line of Symmetry

 

Vertical Alignment

Previous Benchmarks

 

Next Benchmarks

 

Purpose and Instructional Strategies

The purpose of this benchmark is for students to draw lines of symmetry and identify line- symmetric figures. In Grade 2, students identify lines of symmetry in a two-dimensional figure by partitioning (e.g., folding) it and matching its halves. In addition, students in Grade 3 also developed the understanding that a figure can have no lines of symmetry, exactly 1 line of symmetry, or more than 1 line of symmetry. 
  • During instruction, teachers should continue encouraging students to partition figures and match their halves to identify line(s) of symmetry (MTR.2.1). 
  • Instruction can also ask students to build generalizations about which two-dimensional figures are line symmetric and why. For example, students could argue that all squares share similar defining attributes and only differ in size, therefore all squares will be line- symmetric (MTR.2.1, MTR.4.1). 
  • Instruction builds a foundation for exploring reflections in middle school.

 

Common Misconceptions or Errors

  • Students can miss identifying all lines of symmetry in line-symmetric figures. Encourage classroom discussions and have students justify their arguments about lines of symmetry using their partitioned representations.

 

Strategies to Support Tiered Instruction

  • Teacher provides figures that have at least one line of symmetry and tells how many lines of symmetry the figure has. Students draw lines to show where the lines of symmetry would be. 
    • For example, the teacher provides students with images similar to those shown below and has students draw the number of lines of symmetry given and explain how they know the lines they draw are lines of symmetry. 

Symmetry lines

  • Teacher provides a figure partitioned in different ways with dotted lines. Students fold the image along the dotted line and determine if it is a line of symmetry (do the two sides match).
    • For example, the teacher gives a triangle like the one shown below. Students fold along the dotted lines and determine if it shows a line of symmetry or not.

Triangles

 

Instructional Tasks

Instructional Task 1 

Mika says that the uppercase letter H below has 1 line of symmetry. Errol says that the uppercase letter H has 2 lines of symmetry. Who is correct? Show your thinking.
H

 

Instructional Items

Instructional Item 1 

Select all the figures that have at least one line of symmetry. 

AGHRQ

Instructional Item 2 

How many lines of symmetry does the following figure have? 

A

Instructional Item 3 

A figure is shown. How many lines of symmetry does the figure have? 

X

 

*The strategies, tasks and items included in the B1G-M are examples and should not be considered comprehensive.

 




Related Courses

Course Number1111 Course Title222
5012050: Grade Three Mathematics (Specifically in versions: 2014 - 2015, 2015 - 2022, 2022 and beyond (current))
7712040: Access Mathematics Grade 3 (Specifically in versions: 2014 - 2015, 2015 - 2018, 2018 - 2022, 2022 and beyond (current))
5012055: Grade 3 Accelerated Mathematics (Specifically in versions: 2019 - 2022, 2022 and beyond (current))
5012015: Foundational Skills in Mathematics 3-5 (Specifically in versions: 2019 - 2022, 2022 and beyond (current))


Related Access Points

Access Point Number Access Point Title
MA.3.GR.1.AP.3 Identify line-symmetric two-dimensional figures.


Related Resources

Formative Assessments

Name Description
Identifying and Explaining Symmetry

Students are asked to determine if lines drawn on two-dimensional figures are lines of symmetry and to explain their decisions.

Using Lines of Symmetry

Students are asked to use a line of symmetry to complete a drawing. Additionally, they consider how to describe a line of symmetry.

Line Symmetry

Students are asked to identify line-symmetric figures and then draw the lines of symmetry.

Squares and Lines of Symmetry

Students are asked to determine how many lines of symmetry a square has by drawing the lines of symmetry. Students then consider whether all quadrilaterals have four lines of symmetry.

Image/Photograph

Name Description
Clipart: Geometric Shapes

In this lesson, you will find clip art and various illustrations of polygons, circles, ellipses, star polygons, and inscribed shapes.

Lesson Plans

Name Description
ABC Symmetry

Students will explore the concept of line symmetry in this lesson. Students will explore two-dimensional pictures and decide whether or not each image has symmetry. Students will also fold pre-cut capital letters to decide whether or not each letter has symmetry.

Symmetrical Solutions

Students will use paper cutout and geoboards to find and create lines of symmetry. Students will have the opportunity to work with a partner and independently.

Original Student Tutorial

Name Description
The Symmetry Sisters Save the Day

Help the Symmetry Sisters save the City of Symmetry Line and the State of Arithmetic from the Radical Rat in this interactive tutorial!

Problem-Solving Tasks

Name Description
Lines of symmetry for triangles

This activity provides students an opportunity to recognize these distinguishing features of the different types of triangles before the technical language has been introduced. For finding the lines of symmetry, cut-out models of the four triangles would be helpful so that the students can fold them to find the lines.

Lines of symmetry for quadrilaterals

This task provides students a chance to experiment with reflections of the plane and their impact on specific types of quadrilaterals. It is both interesting and important that these types of quadrilaterals can be distinguished by their lines of symmetry.

Lines of symmetry for circles

This is an instructional task that gives students a chance to reason about lines of symmetry and discover that a circle has an an infinite number of lines of symmetry. Even though the concept of an infinite number of lines is fairly abstract, students can understand infinity in an informal way.

Student Resources

Original Student Tutorial

Name Description
The Symmetry Sisters Save the Day:

Help the Symmetry Sisters save the City of Symmetry Line and the State of Arithmetic from the Radical Rat in this interactive tutorial!

Problem-Solving Tasks

Name Description
Lines of symmetry for triangles:

This activity provides students an opportunity to recognize these distinguishing features of the different types of triangles before the technical language has been introduced. For finding the lines of symmetry, cut-out models of the four triangles would be helpful so that the students can fold them to find the lines.

Lines of symmetry for quadrilaterals:

This task provides students a chance to experiment with reflections of the plane and their impact on specific types of quadrilaterals. It is both interesting and important that these types of quadrilaterals can be distinguished by their lines of symmetry.

Lines of symmetry for circles:

This is an instructional task that gives students a chance to reason about lines of symmetry and discover that a circle has an an infinite number of lines of symmetry. Even though the concept of an infinite number of lines is fairly abstract, students can understand infinity in an informal way.



Parent Resources

Image/Photograph

Name Description
Clipart: Geometric Shapes:

In this lesson, you will find clip art and various illustrations of polygons, circles, ellipses, star polygons, and inscribed shapes.

Problem-Solving Tasks

Name Description
Lines of symmetry for triangles:

This activity provides students an opportunity to recognize these distinguishing features of the different types of triangles before the technical language has been introduced. For finding the lines of symmetry, cut-out models of the four triangles would be helpful so that the students can fold them to find the lines.

Lines of symmetry for quadrilaterals:

This task provides students a chance to experiment with reflections of the plane and their impact on specific types of quadrilaterals. It is both interesting and important that these types of quadrilaterals can be distinguished by their lines of symmetry.

Lines of symmetry for circles:

This is an instructional task that gives students a chance to reason about lines of symmetry and discover that a circle has an an infinite number of lines of symmetry. Even though the concept of an infinite number of lines is fairly abstract, students can understand infinity in an informal way.



Printed On:4/26/2024 2:36:18 PM
Print Page | Close this window