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Computer science · Grades 7–12

Data quality and privacy-aware design

Collect only what a task needs and distinguish missing values from zero.

Make a worksheet

Learn the idea

Data

A field should have a clear definition and appropriate type.

Missing

Missing data and a measured zero are different states.

Minimize

Avoid collecting personal details that are unnecessary for the stated purpose.

Access

Private information requires appropriate access controls, not just an unlisted page.

Worked examples

Is an unrecorded score the same as a measured score of zero?

Missing means unknown or absent, not necessarily zero.

No.

Three recorded values are 4, 6 and 8. Ignoring one explicitly missing value, find the mean of the recorded values.

The sum 18 divided by three recorded values is 6.

6

Check your understanding

  1. Which field is unnecessary for an anonymous arithmetic practice tool?

    1. Chosen answer.
    2. A child's home address.
    3. Question difficulty.

  2. Why is a hidden URL not the same as authenticated access?

  3. Which data definition is clearer?

    1. Time in seconds from start to submission.
    2. Number of things.
    3. Time with no units or starting event.

Answers and marking notes

Answers and marking notes
  1. A child's home address.

    Collecting an address is not needed for basic practice.

  2. Someone who obtains or guesses the link may still access it without proving identity.

    Access controls must match the privacy requirement.

  3. Time in seconds from start to submission.

    Definitions make records comparable.

Further reading and review references

These are reference links, not copied exercises, institutional endorsement or proof of independent review.

Independent educational review required. Grade bands are approximate; these are not officially aligned curricula.