Reflection: Vertical Alignment Equivalent Transformations and Symmetry - Section 4: Symmetry: Having the Students Unpack the Standard


In the Grade 4 Common Core Math Standards, there exists: 

  • CCSS.Math.Content.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.

This might lead one to wonder about my inclusion of the Alphabet Symmetry task in a high school geometry lesson.  I think it is helpful for students to apply new ideas in familiar situations. For example, the level of understanding has been taken up a notch here, as the students also look for new concepts like point symmetry.  

Additionally, my students had very productive discussions with an interesting, but meaningful perspective: How does the choice of font impact the symmetry of the alphabet? 

  • Could "K" be drawn so that it does have line symmetry? 
  • Does this O have only two lines of symmetry?
  • Could O have been drawn so that it has an infinite number of lines of symmetry? 
  • How could Q be drawn so that it has line symmetry?

I found this to be a worthwhile exercise in which students generated a number of interesting conjectures and demonstrated their facility with mathematical practices (MP2, MP3).

  Vertical Alignment: Is This Exercise in Alphabet Symmetry Appropriate for High School?
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Equivalent Transformations and Symmetry

Unit 4: Transformations
Lesson 4 of 6

Objective: SWBAT find rotations and reflections that map a figure onto itself, and find single transformations that are equivalent to a composition of transformations.

Big Idea: Symmetry in terms of reflections and rotations. Students unpack the standard and solidify their knowledge of compositions of transformations.

  Print Lesson
Math, Geometry, Symmetry, Constructions and Transformations, dilation, reflection, transformation, horizontal, vertical, translations, rotations, point symmetry
  90 minutes
image symmetry
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