Symmetry is seen all around us and can be taken for granted. It is present in nature, as well as in most man-made objects around us. Why do we like it so much? It is aesthetically pleasing and it has useful functions think of bridges and towers).
Why teach Symmetry? The hands-on activities that are required for the learning of this concept reinforces the concept of left and right and allow for the increase of students’ dexterity and hand-eye co-ordination e.g. cutting out and folding of shapes. I think that it will also help students to develop a sense of Aesthetics congruence to help them imagine and visualize (using abstract thinking).
Some resources for teaching symmetry are:
Pictures – Simple pictures of objects that are symmetrical in shape, some can have only one line of symmetry. Also, pictures of irregular shaped objects are to be used to give students precise criteria for symmetry.
Ink blots – For reflections. Ink is blotted to one side of a page, when the page is folded the blot pattern is superimposed onto the other side. It is important to point out to students that the folded crease becomes the line of symmetry.
A Geoboard – This can be used for building geometrical designs with rubber bands on the geoboard. First, you stretch a rubber band down the center to make a line, then make a design or shape on one side and another student creates its mirror image on the other side.
Dot grids – Students connect the dots on grid paper to create symmetrical shapes and to predict and complete the missing congruent half of the shape.
Symmetrical plane shapes – Paper shapes, wooden shapes, foam shapes, felt shapes, etc. The wooden shapes are very durable, I have never needed to replace mine. However, the paper, felt, and foam shapes are bendable and this is important because it allows students to bend and fold the shapes to find out if they have symmetry.
Mirrors – There’s the mirror and there’s the mira. There is a possible element of danger if you are using mirrors in the classroom. What if it breaks? The mira (also called a geo-reflector) works almost like a mirror but not quite. It is used specifically for teaching symmetry and it is safe for classroom use. Read more about it here and here.
Non-symmetrical plane shapes – as non-examples, to show that not all shapes have symmetry (irregular shapes).
I keep my own collection of paper shapes that I print on colored paper from a template. This is my collection for my students to fold to find symmetry. Click here or on the pictures below to download it for free!
You may also be interested in the symmetry book project my students did…