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.

Students are able to…

  • Identify that a line of symmetry divides a shape into two congruent parts.
  • Recognize lines of symmetry within shapes.
  • Understand that a shape can have multiple lines of symmetry.

[divider] [/divider]Students are able to…because teachers:

  • Ensure students have experience drawing, cutting and folding lines of symmetry.
  • Use a variety of shapes, regular and non-regular, to have students identify if and how many lines of symmetry exist within the shape.

[divider] [/divider]Questions to ask students:

  • Provide a shape.   Identify if it has any lines of symmetry.  How do you know?
    • Sample answer that indicates understanding:  This shape has 1 line of symmetry because if I fold the shape it has 2 congruent parts and doesn’t overlap.  
  • Point to a shape that students have already drawn a line of symmetry for and ask… Can you explain how you know that is a line of symmetry?
    • Sample answer that indicates understanding: If I were to fold the shape in half on that line there would be two matching parts.
    • Sample answer that indicates an incomplete understanding or a misconception: Because I cut it in half.
  • Draw a shape with more than one line of symmetry.  How do you know it has more than 1 line?  
    • Sample answer that indicates understanding:  I can fold it different ways to create two congruent parts that do not overlap.  

[divider] [/divider]FSA Notes

Cognitive Complexity Level: 2 – Basic Application of Skills and Concepts

Achievement Level Descriptors:

2- recognizes a line of symmetry in a two-dimensional figure

3- identifies line-symmetric figures and draws lines of symmetry for two-dimensional figures

4- identifies figures with more than one line of symmetry

5- constructs a figure with a specified number of lines of symmetry

Assessment Limits:

Items that require constructing lines of symmetry must specify the shape category with regard to the number of sides (quadrilateral, triangle, pentagon, etc.).

Items that include trapezoids must consider both the inclusive and exclusive definitions.

Items may not use the term “kite” but may include the figure.

[divider] [/divider]Additional Resources:

Additional in depth content knowledge

Video: Identify line symmetry in regular polygons

[divider] [/divider]Sample Formative Assessment Tasks:

 

Resources/Tasks to Support Your Child at Home

Look for real-world objects in books, around your home or in the newspaper that have lines of symmetry. Could extend and have your child look for objects that have 2 or more lines of symmetry.

Khan Academy: Identifying Symmetrical Figures