Mathematics

Geometry

The most common mistakes Singapore primary students make in Geometry, distilled from 155+ MOE-aligned questions across P3, P4, P5, P6. Free practice at every level.

From the question bank

Top 10 mistakes in Geometry

  1. #1Misconception

    Meet at vertex B — perpendicular, not parallel.

    Seen in 1 question

  2. #2Misconception

    Meet at vertex A — perpendicular, not parallel.

    Seen in 1 question

  3. #3Partial logic

    BC∥DA is correct, but 'only' is wrong; AB∥CD also.

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  4. #4Partial logic

    Counted only the horizontal bars (2) and forgot that each horizontal bar pairs with each vertical bar separately.

    Seen in 1 question

  5. #5Calc error

    Added the number of horizontal bars (2) and vertical bars (2), then subtracted 1, giving 2 + 2 − 1 = 3, instead of multiplying.

    Seen in 1 question

  6. #6Partial logic

    This answer finds the sum of one of each pair of faces (lb + bh + lh = 160 + 224 + 560 = 944) but forgets that a cuboid has 6 faces arranged in 3 identical pairs — the total must be multiplied by 2.

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  7. #7Partial logic

    This answer adds only the top/bottom faces and the two long side faces: 2(20 × 8) + 2(20 × 28) = 320 + 1120 = 1440. It leaves out the two short side faces (8 × 28), which are also part of the net.

    Seen in 1 question

  8. #8Partial logic

    This answer includes the two short side faces and the two long side faces: 2(8 × 28) + 2(20 × 28) = 448 + 1120 = 1568. It leaves out the two top and bottom faces (20 × 8), which are also part of the net.

    Seen in 1 question

  9. #9Misconception

    Different views of a rectangular prism show different 2D shapes depending on the viewing angle.

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  10. #10Misconception

    The front view is not always a square; it depends on the prism's dimensions.

    Seen in 1 question

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