In this third and final illustration in this section on Similar and Different Shapes, we take another look at Choosing a Shape to Complete a Set. As you will remember, there are two ways these questions can appear – as “Find the odd one out” or “Find the shape most like”. They are both testing the same idea though – finding commonalities between shapes and symbols.
We are still looking at the Similar Shapes format here, so the questions take exactly the same form that we showed you in the previous lesson.
Two shapes or symbols are presented to candidates, and they will share one or more characteristics. They are also presented with a choice of four or five other shapes or patterns, and tasked with finding the one which is most similar to the first i.e. the one with the same characteristics.
In this illustration we shall be looking at a slightly harder form of these – ones in which multiple characteristics are shared. Let’s show you an example:
On the left are two figures that have something in common. Which of the remaining five figures is most like the figures on the left?
What might they be looking for here? The first thing to do is run through what the two figures on the left have in common.
We might find that some elements are relevant in our answering the question, but others may be red herrings. It’s also worth noting what is different, as this may save us work later on.
Note that the main shapes are four-sided but not identical, even taking rotation into account. They do, however, have symmetry – they both have rotational and reflective symmetry.
They have lines running through them from corner to corner, but not in the same directions in both shapes. The lines also cross at ninety degrees to each other.
The little shapes at the ends of the lines are identical at top and bottom, but are not the same on each line.
Now we can present the information in a table:
|Shape||Four sided, symmetrical main shape||Lines with same object at each end||Lines through corners||Lines intersect at ninety degrees|
As usual, it’s crazy to expect your child to write a table out during a test; this has to be used to explain things to a child who does not understand, but anyone who can pass this sort of test will need to be able to do everything mentally after a while.
Now, let’s look back to the results – which of the five shapes has the most in common with the two initial shapes?
It appears to a choice between ‘a’ and ‘d’ as they share three of the four characteristics; the other symbols only tick one box each and can be discounted.
Shape ‘d’ is four sided, and symmetrical (if you rotate it, it will appear back on itself after 180 degrees), but the lines do not intersect at ninety degrees.
Shape ‘a’ has not got four sides and the lines go through the inner corners rather than the outer points.,p>We need to decide – I would say the main shape is much more important than the angle of the bisecting lines, so the answer is ‘d’.
Always tell your child to pick the obvious over the obscure. There is usually something quite clear-cut which will just need finding. If in doubt, use any apparent information, however obscure it sems.
So, now you know all there is to know about Similar Shapes questions in the exam and, more importantly, how to answer them. It’s time to try some practise questions out. We have 7 Similar Shapes questions on the Education Quizzes site. Go through each one with your child and, if they have any difficulties, show them the techniques we’ve taught you here.
For your convenience, here are links to each individual quiz: