Justifying keeping or removing a data item

Name:

Date:

Class:

Quick Questions

Shade in the A or B circle for each question.

1. A school canteen app asks for each student's home address. Which is the better justification for REMOVING it?

A The canteen app does not need the home address because orders are picked up at school, so it can be removed.

B Remove the home address because it feels private.

2. Which sentence starter shows a justification for KEEPING a data item?

A Everyone else collects this so...

B The system needs this because...

3. A library app records a student's email so it can send a reminder when a book is overdue. Which justification is complete?

A The app needs the email because emails are useful.

B The app needs the email because it sends overdue reminders, which is the purpose of the system.

4. You want to test whether a data item can be removed. What should you do?

A Remove the item and check that the system still works.

B Keep the item in case someone wants it later.

5. A quiz app works fine after you delete the 'favourite colour' field. What does this tell you?

A The field was not needed, so it can be removed.

B The field was essential, so it must be put back.

Match the Pairs

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

Left column		Right column
1The system needs this because...		AHome address is needed by the pizza app because it must deliver the order to the right door.
2Remove the item, then check the system still works		BA sentence starter that begins a justification for keeping a data item by giving a reason linked to the system's purpose
3A good justification names the data item, the system's purpose and a because reason		CThe reason does not link to the system's purpose. 'We always have' is a habit, not a reason the item is needed.
4A data item can be essential for one purpose but not another		DA test to decide if a data item is really needed: if the system still does its job without it, the item can be removed
5We collect phone numbers because we always have.		EBirthday: needed to check age for a licence form, but not needed for a library book return.
6Remove the email field. The sign-up form is now broken, but that is fine.		FThe student removed the item but ignored the test. If the system stops working, the item is probably essential and should be kept.

Definitions

The system needs this because

Fill in the Blanks

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

Item: email, Purpose: send receipts The system needs this _______ it sends the receipt to the buyer.

Item: home address Purpose: class quiz app Test: ______ it, then check the app works.

Item: home address Delivery: _________ as parcels need it Quiz app: not needed, so remove it

Data item: phone number _______: contact parents about trips Keep it because trips need a contact.

Test: removed email, login stopped working Result: ____ it because login needs it

Spot the Error

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

Question 1

A Item: favourite colour

B System: parcel delivery

C Needed because: the parcel

D must reach the right door

Question 2

A Item: parent email

B Purpose: collect more data

C The system needs this because

D it emails news to families.

Question 3

A The system needs this anyway

B allergy info keeps students

C safe at the canteen.

Question 4

A Item: school year level

B System: sports carnival app

C Needed because: I like it

D Remove it: sorting would fail

Question 5

A System: swimming club sign-up

B Test: remove middle name: OK

C Verdict: keep it, it is needed

D Because it works without it

Answer Key

Justifying keeping or removing a data item

Section A: Quick Questions

A — The canteen app does not need the home address because orders are picked up at school, so it can be removed.

B — The system needs this because...

B — The app needs the email because it sends overdue reminders, which is the purpose of the system.

A — Remove the item and check that the system still works.

A — The field was not needed, so it can be removed.

Section B: Match the Pairs

The system needs this because... → A sentence starter that begins a justification for keeping a data item by giving a reason linked to the system's purpose

Remove the item, then check the system still works → A test to decide if a data item is really needed: if the system still does its job without it, the item can be removed

A good justification names the data item, the system's purpose and a because reason → Home address is needed by the pizza app because it must deliver the order to the right door.

A data item can be essential for one purpose but not another → Birthday: needed to check age for a licence form, but not needed for a library book return.

We collect phone numbers because we always have. → The reason does not link to the system's purpose. 'We always have' is a habit, not a reason the item is needed.

Remove the email field. The sign-up form is now broken, but that is fine. → The student removed the item but ignored the test. If the system stops working, the item is probably essential and should be kept.

Section C: Definitions

The system needs this because — A justification names the data item, the system's purpose and gives a because reason why the item is needed or could be removed. Test it by removing the item and checking the system still works.

Section D: Fill in the Blanks

Item: email, Purpose: send receipts
The system needs this because
it sends the receipt to the buyer.

Item: home address
Purpose: class quiz app
Test: remove it, then check the app works.

Item: home address
Delivery: essential as parcels need it
Quiz app: not needed, so remove it

Data item: phone number
Purpose: contact parents about trips
Keep it because trips need a contact.

Test: removed email, login stopped working
Result: keep it because login needs it

Section E: Spot the Error

A — The data item must match the because reason. A parcel reaching the right door needs the home address, not a favourite colour. The line should be 'Item: home address'.

B — A purpose says what the system is for. 'Collect more data' is not a real purpose and cannot justify keeping an item. It should name a real job, such as 'Purpose: send the class news'.

A — A justification uses the sentence starter 'The system needs this because...' so that a reason follows. 'Anyway' gives no reason. The line should be 'The system needs this because'.

C — A because reason must link the item to the system's purpose. 'I like it' is a personal opinion, not a reason. It should say why the system needs it, such as 'Needed because: it sorts teams'.

C — The removal test showed the sign-up still works without the middle name. The verdict must match the test, so it should be 'Verdict: remove it, not needed'.