Direct and indirect identifiers

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. Which one is a direct identifier?

A A student's full name

B A student's year level

2. Which one is an indirect identifier?

A Postcode

B Email address

3. True or false: An email address like ava.nguyen@school.edu.au is a direct identifier.

A True

B False

4. Which statement about indirect identifiers is correct?

A They can never be used to identify anyone

B They can identify someone when combined with other details

5. A dataset has only age and school. Which is more accurate?

A Both are indirect, so no one can ever be found

B Combining them could narrow it down to one student

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1email = "ava.nguyen@mail.com"		AYear level is an indirect identifier, not a direct one. Many students share it, so it does not point to one person alone.
2postcode = 3350		BRemoving the name is not enough. Birth date, suburb and school are indirect identifiers that can be combined to find one person.
3Combining indirect details such as age, school and suburb can narrow a group down to one person		CA direct identifier that points to one person by itself
4A name column is a direct identifier, so it is removed to protect privacy		Dage = 13 AND school = "Hill High" AND suburb = "Ballarat"
5Direct identifier: yearLevel = 8		EAn indirect identifier that only helps identify someone when combined with other details
6Safe to share: name removed, but birth date + suburb + school kept		FALTER TABLE students DROP COLUMN firstName;

Definitions

direct and indirect identifiers

Fill in the Blanks

Complete each line of code by filling in the missing parts.

SELECT ________ FROM students;

SELECT _________, house FROM students;

SELECT house, yearLevel FROM students _____ yearLevel = 7;

SELECT firstName FROM students WHERE house = 'Red' ___ yearLevel = 7;

SELECT _____(*) FROM students WHERE yearLevel = 7 AND house = 'Red';

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A field = "email"

B kind = "indirect"

C print(field, kind)

Question 2

A field = "postcode"

B alone = False

C kind = "direct"

D print(field, kind)

Question 3

A direct = ["name", "suburb"]

B indirect = ["age", "school"]

C print(len(direct))

Question 4

A fields = ["name", "age"]

B if "name" in fields:

C print("Indirect identifier")

Question 5

A details = ["age" "suburb", "school"]

B count = len(details)

C if count >= 3:

D print("Could identify one")

Answer Key

Direct and indirect identifiers

Section A: Quick Questions

A — A student's full name

A — Postcode

A — True

B — They can identify someone when combined with other details

B — Combining them could narrow it down to one student

Section B: Match the Pairs

email = "ava.nguyen@mail.com" → A direct identifier that points to one person by itself

postcode = 3350 → An indirect identifier that only helps identify someone when combined with other details

Combining indirect details such as age, school and suburb can narrow a group down to one person → age = 13 AND school = "Hill High" AND suburb = "Ballarat"

A name column is a direct identifier, so it is removed to protect privacy → ALTER TABLE students DROP COLUMN firstName;

Direct identifier: yearLevel = 8 → Year level is an indirect identifier, not a direct one. Many students share it, so it does not point to one person alone.

Safe to share: name removed, but birth date + suburb + school kept → Removing the name is not enough. Birth date, suburb and school are indirect identifiers that can be combined to find one person.

Section C: Definitions

direct and indirect identifiers — A direct identifier, like a name or email, points to one person alone. An indirect identifier, like suburb, age or school, only identifies someone when combined with other details.

Section D: Fill in the Blanks

SELECT lastName FROM students;

SELECT yearLevel, house FROM students;

SELECT house, yearLevel FROM students
WHERE yearLevel = 7;

SELECT firstName FROM students
WHERE house = 'Red' AND yearLevel = 7;

SELECT COUNT(*) FROM students
WHERE yearLevel = 7 AND house = 'Red';

Section E: Spot the Error

B — An email address points to one person by itself, so it is a direct identifier. Line 2 should be kind = "direct".

C — A postcode is shared by many people, so it only identifies someone when combined with other details. It is an indirect identifier, so line 3 should be kind = "indirect".

A — A suburb is shared by many people, so it is an indirect identifier. The direct list should hold name and email, so line 1 should be direct = ["name", "email"].

C — The check finds a name, which points to one person alone. The message on line 3 should say Direct identifier.

A — There is a comma missing between "age" and "suburb". Line 1 should be details = ["age", "suburb", "school"].