Mathematics

Angles

The most common mistakes Singapore primary students make in Angles, distilled from 165+ MOE-aligned questions across P3, P4, P5, P6. Free practice at every level.

From the question bank

Top 10 mistakes in Angles

  1. #1Calc error

    Missed one corner.

    Seen in 2 questions

  2. #2Misconception

    Straight = 180°.

    Seen in 2 questions

  3. #3Misconception

    A pentagon has 5 corners, not 4. Even if some corners are right angles, a regular pentagon has angles of 108° at each corner, not 90°.

    Seen in 1 question

  4. #4Misconception

    A triangle has only 3 corners, not 4. Even if one corner is a right angle, a triangle can never have 4 right angles.

    Seen in 1 question

  5. #5Misconception

    A trapezium has 4 corners but typically only 2 are right angles (in a right trapezium). Not all 4 corners of a trapezium are right angles.

    Seen in 1 question

  6. #6Misconception

    You read off the OUTER scale (which goes the opposite way) instead of the INNER scale. The question says one arm lines up with 0° on the INNER scale, so you must read the inner scale at the other arm. The outer scale shows 45° at the same spot, but the correct reading is 135°.

    Seen in 1 question

  7. #7Calc error

    You computed 180° − 125° or read the outer scale and added 10°. The correct reading is the value on the inner scale where the second arm lands, which is 135°.

    Seen in 1 question

  8. #8Calc error

    You misread the scale by 10°. The arm points to the 135° mark, not 145°. Take care to read the exact line on the protractor, not one tick further.

    Seen in 1 question

  9. #9Calc error

    You used 90° − 55° = 35° instead of 145° − 90°. The 145° angle is the WHOLE that is being split into 90° (pole-to-ground) and the unknown part. So unknown = 145° − 90° = 55°, not 35°.

    Seen in 1 question

  10. #10Calc error

    You may have computed 155° − 90° = 65° (using 155 instead of 145). Reread the question: the total angle is 145°, not 155°. So 145° − 90° = 55°, not 65°.

    Seen in 1 question

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