Deciding between a decision and a repeat

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Quick Questions

Shade in the A or B circle for each question.

1. You only take an umbrella if it is raining. Which do you use?

A REPEAT (a loop)

B IF (a decision)

2. You need to write 'Wash one plate' for all 20 plates in the sink. Which fits best?

A REPEAT 20 times

B IF there is a plate

3. Which step should go inside an IF?

A Put on a jacket only if it is cold

B Clap your hands 10 times

4. Which algorithm needs a REPEAT?

A Stir the soup until it is thick

B Wear a hat if it is sunny

5. A game checks every coin on the screen. If a coin is gold, it adds 5 points. What does it need?

A Only an IF and no REPEAT

B Both: a REPEAT with an IF inside

Match the Pairs

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

Left column		Right column
1IF it is raining THEN take an umbrella		AThis claps 10 times, but the clapping was meant to happen only sometimes, such as only if the song is playing. It needs an IF.
2REPEAT 5 TIMES: jump		BThe same step is written out again and again. A REPEAT 3 TIMES would do this job with one step.
3Use a decision when a step only happens sometimes, like packing a raincoat only if it is raining		CA repeat: the same step happens many times, here 5 jumps.
4Use both together when a loop needs a choice inside, like checking every day of the week for rain		DREPEAT 7 TIMES: IF raining THEN pack raincoat
5IF it is raining THEN take umbrella take umbrella take umbrella		EA decision: the step happens only sometimes, when it is raining.
6REPEAT 10 TIMES: clap		FIF raining THEN pack raincoat

Definitions

IF or REPEAT

Fill in the Blanks

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

__ it is raining THEN take an umbrella

______ 10 TIMES do a star jump

REPEAT 5 TIMES __ the ball is red THEN put it in the red box

REPEAT _____ the bowl is full pour in more water

______ UNTIL the bin is empty IF the item is plastic THEN put it in recycling

Spot the Error

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

Question 1

A SET stars TO 0

B SAY Drawing stars

C IF 10 TIMES

D ADD 1 TO stars

E END REPEAT

Question 2

A ASK is it raining

B SET weather TO answer

C REPEAT UNTIL weather = rain

D TAKE umbrella

E END IF

Question 3

A SET plates TO 8

B IF plates = 8 THEN

C WASH plate

D END REPEAT

Question 4

A SET wet TO 0

B REPEAT 7 TIMES

C CHECK the sky

D REPEAT raining THEN

E ADD 1 TO wet

F END IF

Question 5

A SET pages TO 0

B REPEAT UNTIL pages = 20

C READ a page

D SET pages TO 1

E END REPEAT

Answer Key

Deciding between a decision and a repeat

Section A: Quick Questions

B — IF (a decision)

A — REPEAT 20 times

A — Put on a jacket only if it is cold

A — Stir the soup until it is thick

B — Both: a REPEAT with an IF inside

Section B: Match the Pairs

IF it is raining THEN take an umbrella → A decision: the step happens only sometimes, when it is raining.

REPEAT 5 TIMES: jump → A repeat: the same step happens many times, here 5 jumps.

Use a decision when a step only happens sometimes, like packing a raincoat only if it is raining → IF raining THEN pack raincoat

Use both together when a loop needs a choice inside, like checking every day of the week for rain → REPEAT 7 TIMES: IF raining THEN pack raincoat

IF it is raining THEN take umbrella take umbrella take umbrella → The same step is written out again and again. A REPEAT 3 TIMES would do this job with one step.

REPEAT 10 TIMES: clap → This claps 10 times, but the clapping was meant to happen only sometimes, such as only if the song is playing. It needs an IF.

Section C: Definitions

IF or REPEAT — Use IF when a step happens only sometimes. Use REPEAT when the same steps happen many times. Use both together when a loop needs a choice inside.

Section D: Fill in the Blanks

IF it is raining THEN
  take an umbrella

REPEAT 10 TIMES
  do a star jump

REPEAT 5 TIMES
  IF the ball is red THEN
    put it in the red box

REPEAT UNTIL the bowl is full
  pour in more water

REPEAT UNTIL the bin is empty
  IF the item is plastic THEN
    put it in recycling

Section E: Spot the Error

C — Adding a star is the same step done many times, so it needs REPEAT 10 TIMES. IF is only for a step that happens sometimes.

C — You only take an umbrella sometimes, when it is raining. That is a decision, so the line should be IF weather = rain THEN.

B — Washing a plate is the same step done many times, so it needs REPEAT 8 TIMES. An IF would only wash plates once, and only if there are 8.

D — Adding to wet should happen only on some days, when it is raining. That needs a decision, so the line should be IF raining THEN.

D — Setting pages to 1 inside the loop resets the count every time, so pages never reaches 20 and the loop never stops. It should be ADD 1 TO pages.