Figure Classification (Odd One Out)
Figure Classification, also called the odd-one-out question, is a regular topic of the non-verbal reasoning part of the ADRE 3.0 Grade IV paper. In this type of question a set of four or five figures is given, and all but one of them share a common property. The candidate has to find the figure that does not follow the common rule. The topic tests close observation, the ability to find similarities and differences, and quick judgement about the properties of shapes. Because no language and no calculation is involved, the question is fair and purely visual, but the properties that separate the figures can be surprisingly small, so the candidate must look carefully at every figure before deciding.
Meaning of a Figure Classification Question
In a figure classification question the figures are placed side by side and the instruction is to choose the one that is different from the rest. The key is to find the property that is common to the majority of the figures; the single figure that lacks that property is the answer. The common property may relate to the number of sides, the presence of a curved or a straight line, the number of parts, the position of a dot, the type of symmetry, or the way the figure is shaded. Once the common property is discovered, the odd figure stands out at once.
What Can Make a Figure Different
- Number of sides, corners or line segments.
- Presence of a curved line against only straight lines.
- Open figures against closed figures.
- Number of dots, circles or small marks inside the figure.
- Position of a dot such as inside, outside or on the boundary.
- Type of symmetry, for example vertical, horizontal or none.
- Shaded parts against unshaded parts.
- Number of regions into which the figure is divided.
- Equal or unequal length of the sides.
- Direction in which an element such as an arrow points.
Types of Figure Classification
Some questions are based on geometry, where the figures differ in the number of sides or in the number of lines. Some are based on symmetry, where one figure has no line of symmetry while the others have one. Some are based on the number of elements such as dots or tiny circles. Some are based on shading, where a small portion is shaded in all figures except one. There are also questions based on rotation, where all figures are the same shape seen in different positions but one is a mirror image, and questions based on dimension, where all figures except one are two-dimensional or three-dimensional.
How to Solve a Figure Classification Question
- Look at all the figures together and ask what they have in common.
- Count the sides, lines, dots and shaded parts of each figure.
- Check the shape for symmetry and for curved against straight lines.
- The figure that breaks the common pattern is the answer.
- If more than one figure seems odd, choose the one that differs on the largest number of counts.
Worked Examples
Suppose four figures are triangles and one is a square; the square has four sides while all the others have three, so the square is the odd one out. Suppose four figures are closed and one is an open shape; the open shape is the answer. Suppose four figures each contain a dot at the centre and one has the dot near the edge; the figure with the dot at the edge is different. Suppose three figures have a vertical line of symmetry and one does not; the figure without symmetry is the answer. In each case the answer is found by naming the common property in words.
How This Topic Appears in the Examination
Figure classification is usually asked as a small cluster of objective questions carrying one mark each. The figures are simple, but they are drawn very close to one another on purpose so that a careless glance misses the real difference. The candidate is expected to solve each question in about half a minute to one minute. Because the topic does not involve calculation, it is a good source of quick marks for candidates who train their eyes to notice small differences in shape, shading and position.
Memory Tips
Always run through the same mental list for every question: sides, curves, closed or open, dots, symmetry, shading and number of parts. Do not fix your attention on the first figure, because the odd figure may be anywhere in the row. When all the figures look alike, look at the smallest element such as a dot or a tiny line, since the difference is often hidden there. Try to describe the common property in one short sentence; if you can, you have almost certainly found the answer.
Common Mistakes to Avoid
- Choosing a figure that only looks different without checking a property.
- Counting the elements carelessly, especially the number of lines.
- Ignoring symmetry and shading while checking only the number of sides.
- Missing an open figure among closed figures.
- Giving up too early when the difference is in a very small detail.
How to Prepare This Topic
- Revise the basic properties of triangles, quadrilaterals and circles.
- Practise at least twenty odd-one-out questions every day.
- For every question, write down the common property in one line.
- Learn the common types of symmetry and recognise them quickly.
- Time yourself and aim to finish each question within a minute.
Additional Solved Examples
If four figures are two-dimensional and one is a cube or a cylinder, the three-dimensional figure is the odd one out because the rest are flat. If four figures contain an even number of dots and one contains an odd number, the figure with the odd number is different. If four figures are divided into three parts each and one is divided into four, the one with four parts is the answer. If three figures show a circle with an inner line and one shows a circle without the inner line, the figure missing the inner line is odd. These examples show that the answer changes with the property being tested, so it is the property, not the shape, that must be judged.
Advanced Tips
When two figures seem equally different, count how many properties each one breaks; the figure that breaks two properties is far more likely to be the answer than a figure that breaks only one. Look at the figures in a fixed order from left to right so that no figure is skipped. In symmetry questions, fold the figure mentally along the middle; a true line of symmetry makes the two halves coincide. In shading questions, note whether the shaded part is in the same relative position in all figures. If the paper is difficult, leave the question and come back, because a fresh eye often spots the difference immediately.
Related Non-Verbal Topics
Figure Classification is closely related to Figure Analogy, Figure Series and Embedded Figures. Analogy requires a rule between pairs, while classification requires a rule within a group, and both depend on the same careful observation. Series requires the continuation of a pattern, which also depends on noticing what changes and what stays the same. Embedded figures requires finding a shape inside a larger drawing, which sharpens the eye for outlines. Practising these topics together builds the general visual skill that the whole non-verbal section rewards.
Quick Revision Checklist
- Find the property common to most figures.
- Count sides, lines, dots and shaded parts.
- Check curved against straight and open against closed.
- Check symmetry along the middle of the figure.
- Look at the smallest detail if nothing else differs.
- State the common property in one sentence before answering.
Frequently Asked Questions
What is a figure classification question?
It gives a group of similar figures and asks you to pick the one figure that does not share the common property of the rest.
What properties are usually tested?
The number of sides, curved or straight lines, open or closed shapes, dots, symmetry, shading and the number of parts are the most common properties.
How do I find the odd figure quickly?
Name the property that is common to the majority of the figures, then the single figure that lacks that property is the answer.
What if two figures seem different?
Count how many properties each one breaks and choose the figure that breaks the largest number, as it is the intended odd one out.
How much time should each question take?
An easy odd-one-out question should take less than a minute once you are used to checking the common properties.