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Measurement and tolerances for GCSE Engineering

GCSE Engineering, Testing and drawing. Usually met in years 9 to 11.

Convert units, work with tolerances and limits, and calculate volumes and masses of parts.

What you practise

Starts with unit conversions and builds to the mass of a part from its density. Practice moves up a level when a round goes well and down when it does not.

Sample questions

Each sample comes with the method and the reason every wrong option is wrong. Real practice rounds are ten questions at your level.

Sample question, level 2 of 5

A part is drawn as 106 ± 0.25 mm. What is its largest allowed size?

  1. 106.5 mm
  2. 106.25 mm
  3. 105.75 mm
  4. 108.5 mm
  5. 106 mm
Show the answer and method

Answer: B, 106.25 mm

The method: Add the tolerance: 106 + 0.25 = 106.25 mm.

Why the other options are wrong:

  • A, 106.5 mm: The tolerance was used twice.
  • C, 105.75 mm: This is the smallest allowed size.
  • D, 108.5 mm: The decimal point is one place out.
  • E, 106 mm: This is the nominal size, with no tolerance.

Sample question, level 4 of 5

A steel block is 90 mm × 20 mm × 50 mm. What is its volume in cm³?

  1. 9,000 cm³
  2. 900 cm³
  3. 90 cm³
  4. 16 cm³
  5. 90,000 cm³
Show the answer and method

Answer: C, 90 cm³

The method: Volume = 90 × 20 × 50 = 90,000 mm³. There are 1000 mm³ in 1 cm³, so 90,000 ÷ 1000 = 90 cm³.

Why the other options are wrong:

  • A, 9,000 cm³: That divides by 10. 1 cm³ is 1000 mm³.
  • B, 900 cm³: That divides by 100. 1 cm³ is 10 × 10 × 10 = 1000 mm³.
  • D, 16 cm³: The sides were added, not multiplied.
  • E, 90,000 cm³: This is the volume in mm³. There are 1000 mm³ in 1 cm³.

See where this fits: every GCSE option topic and Key Stage 3.

Related topics: Testing and quality, Drawing, CAD and CAM.