Quick Line and Rotational Symmetry Project

A quick project to introduce symmetry:

You can either provide or have them use a protractor to draw some simple geometric shapes on construction paper.  I typically require a square, an equilateral triangle, and a third polygon of their choice.  They will need two identical copies of each shape — one for showing line symmetry and one for showing rotational symmetry.

Line Symmetry: Using dashed lines, students indicate the lines of symmetry on each shape.  You can have them find those lines simply by folding the shape in half or by using a ruler to measure, depending on their skill level.  They fold the shape along each line and then glue it to a poster by putting glue on just one small section.  This allows the shape to still fold along each line after it is mounted.

Rotational Symmetry: Students locate the center of each shape using a ruler.  Attach the shape to the poster with a brad and trace around it.  The shape should be able to turn and demonstrate how the correct rotation makes the shape align with its original position.  To figure out how many degrees the shape must rotate, take a full rotation (360°) and divide it by however many turns it takes to get the object back to its original position.  For example, a square will line up with itself in four different ways.  Three hundred sixty divided by four is ninety, so we say a square has 90° rotational symmetry.

For the finished product, have students decide how many lines of symmetry and how many degrees of symmetry each shape has.  Quick and easy.  Just one more way to give to the hand before we give to the mind.  Thanks, Maria Montessori!

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*It’s worth it to do this (and most other paper projects) on construction paper for the weight and bright colors.  This package is a great deal on Amazon — 500 sheet for under $10.  You’re welcome!

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