Explain why scientists use standard SI units and prefixes when sharing measurements with other scientists around the world.

Edexcel GCSE Physics (1PH0) — 1.1 Key concepts of physics · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Using standard SI units means all scientists use the same units for the same quantities.
This allows measurements to be compared or reproduced without confusion or error.
Prefixes such as kilo, mega or milli are used to express very large or very small quantities.
This makes numbers easier to work with / write, avoiding very long strings of zeros.

Examiner tips

  • Use the exact wording from the mark scheme; include all four points.
  • Show the logical flow: standard units → consistency → comparison/reproducibility; prefixes → scaling convenience.
  • Keep the answer concise, no extra sentences.

Mark scheme (4 marks)

  1. Using standard SI units means all scientists use the same units for the same quantities
  2. This allows measurements to be compared or reproduced without confusion or error
  3. Prefixes such as kilo, mega or milli are used to express very large or very small quantities
  4. This makes numbers easier to work with / write, avoiding very long strings of zeros

Key terms in this question

SI units · prefixes

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