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Year 6 Maths

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Plotting Points on a Grid


In Year 5 you met the idea that you can use co-ordinates to tell where a point was on a grid. If you have an x-axis along the bottom of a page and a y-axis up the side, you can tell where a point on the grid is by a pair of numbers. The first number, x, is how far across the grid the point is. The second number, y, is how far up. Together, they make an ordered pair, which is a way of writing co-ordinates.


Look at quadrilateral ABCD. We are going to translate it, which is something else we first did in Year 5. If we add 3 to each x number and 4 to each y, we get new points which we call A'B'C'D', making a second quadrilateral. The co-ordinates are (5,9), (7,9), (6,8), (5,6).



We need some new terms. We say that A' ("A dashed" or sometimes "A prime") is the image of A. The translation maps A onto its image, A'. The same translation maps quadrilateral ABCE onto its image A'B'C'D'.

A translation means that you add or subtract the same amount to each point. As a consequence, The original image and the new image after the translation are always congruent.

Both images are the same way up and the same way round.



Try plotting some images after some different translations.

We will start with another quadrilateral, JKLM (6,6), (7,8), (8.8), (9,6). Whar special sort of quadrilateral is that?

Translate JKLM 2 units to the left and 5 unites down.

Work out the points of the image, point by point. You need to subtract 2 from each x value and 5 from each y.




This activity is adapted from pages 279-80 of What Your Year 6 Child Needs to Know.