Counting only some things with IF inside a loop

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Quick Questions

Shade in the A or B circle for each question.

1. A loop checks each card in a pile. Which line counts only the red cards?

A IF card = red THEN count ← count + 1

B count ← count + 1 (with no IF)

2. count is 0. The next card is blue. The algorithm says: IF card = red THEN count ← count + 1. What is count afterwards?

A 1

B 0

3. A pile has 5 cards: red, blue, red, red, blue. The loop counts only red cards. What does count end up as?

A 3

B 5

4. Where should the IF go to count only the correct quiz answers?

A Inside the loop, so it checks each answer

B After the loop, so it checks only once

5. A quiz loop has this line: IF answer is correct THEN score ← score + 1. A student gets an answer wrong. What happens to score?

A score goes down by 1

B score stays the same

Match the Pairs

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

Left column		Right column
1IF card = red THEN count ← count + 1		AAdds 1 to the score only when the quiz answer is correct, and leaves the score alone if it is wrong
2IF answer = correct THEN score ← score + 1		BThe count goes up on every turn of the loop, not only for red cards. The add-1 step must come after THEN so it only happens when the card is red.
3When a card is black, the condition is false, so the counter stays the same		CAdds 1 to the counter only when the card being checked is red
4Start the counter at 0, then check every card in the pile and count only the red ones		DIF card = red THEN count ← count + 1
5REPEAT 10 TIMES count ← count + 1 IF card = red THEN say count		EThe counter is reset to 0 instead of adding 1. It should be count ← count + 1 so the red cards are added up.
6count ← 0 REPEAT 10 TIMES IF card = red THEN count ← 0		Fcount ← 0 REPEAT 10 TIMES IF card = red THEN count ← count + 1

Definitions

IF card = red THEN count ← count + 1

Fill in the Blanks

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

FOR EACH card IN pile IF card = red ____ count ← count + 1

REPEAT 10 TIMES __ answer = right THEN score ← score + 1

FOR EACH card IN pile IF card = red THEN count ← count _ 1

count ← _ FOR EACH card IN pile IF card = red THEN count ← count + 1

score ← 0 FOR EACH answer IN quiz IF answer = right THEN score ← _____ + 1

Spot the Error

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

Question 1

A count ← 1

B FOR EACH card IN pile

C IF card = red THEN

D count ← count + 1

E OUTPUT count

Question 2

A score ← 0

B FOR EACH answer IN score

C IF answer = correct THEN

D score ← score + 1

E OUTPUT score

Question 3

A count ← 0

B FOR EACH card IN pile

C IF card = red THEN

D count ← count - 1

E OUTPUT count

Question 4

A redCount ← 0

B FOR EACH card IN pile

C IF card = blue THEN

D redCount ← redCount + 1

E OUTPUT redCount

Question 5

A count ← 0

B REPEAT UNTIL card = red

C take the next card

D IF card = red THEN

E count ← count + 1

F OUTPUT count

Answer Key

Counting only some things with IF inside a loop

Section A: Quick Questions

A — IF card = red THEN count ← count + 1

B — 0

A — 3

A — Inside the loop, so it checks each answer

B — score stays the same

Section B: Match the Pairs

IF card = red THEN count ← count + 1 → Adds 1 to the counter only when the card being checked is red

IF answer = correct THEN score ← score + 1 → Adds 1 to the score only when the quiz answer is correct, and leaves the score alone if it is wrong

When a card is black, the condition is false, so the counter stays the same → IF card = red THEN count ← count + 1

Start the counter at 0, then check every card in the pile and count only the red ones → count ← 0 REPEAT 10 TIMES IF card = red THEN count ← count + 1

REPEAT 10 TIMES count ← count + 1 IF card = red THEN say count → The count goes up on every turn of the loop, not only for red cards. The add-1 step must come after THEN so it only happens when the card is red.

count ← 0 REPEAT 10 TIMES IF card = red THEN count ← 0 → The counter is reset to 0 instead of adding 1. It should be count ← count + 1 so the red cards are added up.

Section C: Definitions

IF card = red THEN count ← count + 1 — Inside a loop, the IF checks each item. Only when the item meets the condition does the counter go up by 1. If the condition is false, the counter stays the same.

Section D: Fill in the Blanks

FOR EACH card IN pile
IF card = red THEN
count ← count + 1

REPEAT 10 TIMES
IF answer = right THEN
score ← score + 1

FOR EACH card IN pile
IF card = red THEN
count ← count + 1

count ← 0
FOR EACH card IN pile
IF card = red THEN count ← count + 1

score ← 0
FOR EACH answer IN quiz
IF answer = right THEN score ← score + 1

Section E: Spot the Error

A — The counter must start at 0 before any cards are checked. Starting at 1 means the final count is always one too high. It should be count ← 0.

B — The loop needs to go through every answer in the quiz, not through the score. It should be FOR EACH answer IN quiz.

D — When a card is red, the counter should go UP by 1, not down. It should be count ← count + 1.

C — We are counting red cards, so the IF must check for red. Checking for blue would count the wrong cards. It should be IF card = red THEN.

B — The loop would stop at the first red card, so the other cards would never be checked. It should repeat 8 times so every card gets checked: REPEAT 8 TIMES.