Skip to main content

Mirror, mirror on the web

Q) Can you inspire a non-specialist mathematician about line symmetry? This is my second year teaching a low ability Year 7 maths group (my specialism is biology). There must be more exciting things to look at than colouring pictures.

A) I have found some great websites you should visit for inspiration. This first one was set up by Adrian Bruce, a teacher in Australia, and his Year 6 class. There are some great interactive activities on this site: www.adrianbruce.comSymmetryabout.htm

For example given half a word what is the full word?

There is also some research on the web on facial symmetry and attractiveness. Apparently, the more symmetrical your face the more attractive you are. Are you racing to the mirror?

In this research the most commonly used method is to create "chimeric faces". A photograph is sliced in two down the centre of the face and three images are created: one of two right-hand-sides (RHS); one of two left-hand-sides (LHS); and the original. I used PowerPoint to do this (see above right).

The class could then investigate symmetry and attractiveness. This could be linked with an IT lesson on image processing software. Though it may not be a good idea for pupils to discuss each other's attractiveness, they could perhaps look at their favourite personalities.

I also found an interesting site on bilateral symmetry in nature ( Scientists have created an experiment to determine human accuracy in observing the symmetry of an array of dots and of insects in varying orientations and found that we seem to be good at detecting mirror symmetry when it is vertical. This site is interactive.

For the artists among the pupils there is an image of half an insect to be completed at www.entm.purdue.eduentomologyoutreachinsectivitySymmetry.pdf

I have found investigating crop circles on the web a successful class activity. Groups of pupils can be given sets of images of crop circles and asked to describe the designs mathematically. For a low ability group it is helpful to have words related to symmetry such as "match, fold, line of symmetry, bilateral symmetry, mirror image, and reflection"on the wall.

Include words of rotational symmetry such as "order of rotational symmetry, centre of rotation".

An alternative is to give a pair of pupils a list of properties of the different crop circles they are to hunt for on the web. For example, find:

* A crop circle with bilateral symmetry.

* A crop circle that has no symmetry.

* A crop circle that has six lines of symmetry.

* A crop circle with rotational symmetry of order three.

Two sites for crop circles are: www.busty-taylor.comcropper98busty2.htm Why teach probability? This is a question I am often asked. The following poem sums up my thoughts on the subject: Possibly Probability

You probably wonder

"Why teach probability in class?"

You probably think

About it's desirability in life.

You probably ask

Of it's suitability in school.

You probably know

It gives credibility to research.

You probably guess

It provides capability for decisions.

You probably understand

Of it's suitability to inform.

You probably learnt in school

It's about the possibility of situations.

You probably became aware

Of this chance to comprehend life's choices.

Email your questions to Mathagony Aunt at Or write to TES Teacher, Admiral House, 66-68 East Smithfield, London E1W 1BX

Log in or register for FREE to continue reading.

It only takes a moment and you'll get access to more news, plus courses, jobs and teaching resources tailored to you