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# Secondary Magazine - Issue 117: Eyes Down

Created on 25 November 2014 by ncetm_administrator
Updated on 16 December 2014 by ncetm_administrator

# Eyes Down

Our monthly picture that you could use with your pupils, or your department, or just by yourself, to make you think about something in a different way

This picture is a snapshot from a Year 7 pupil’s exercise book and shows a common mistake in using algebra notation. The pupil was asked to find the perimeter of the figures (not drawn to scale!). It is intriguing that the pupil can write 6q (not q6) and yet writes a2 instead of 2a.

How would you explore this error with the pupil, and also draw on it for the benefit of the whole class?

• First you could ask the pupil to explain how the answers were reached, without saying which is correct: articulating the reasoning will be instructive, and may lead to self-correction
• It may be helpful to write the terms out in ‘long hand’ which would give a + a + b + b + b + b and then discuss combining the a terms and the b terms.
• You could have a set of numerical expressions such as 3+3, 3x3, 2 x 3 and 32, and ask pupils to match them up. Similar algebraic expressions, eg a + a, a x a, 2a, a2, would then form the next set of cards to match
• You may like to consider the area of the figure, using a diagram

Let us know @NCETMsecondary what you would do

If you have a thought-inducing picture, please send a copy (ideally, about 1-2Mb) to us at info@ncetm.org.uk, with a note of where and when it was taken, and any comments on it you may have.

Image credit

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