Algorithms that use sequence, branching and iteration together

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Quick Questions

Shade in the A or B circle for each question.

1. Which part of an algorithm is a SEQUENCE?

A A step that repeats again and again

B Steps that happen one after another in order

2. Read this step: 'IF it is raining THEN take an umbrella'. What is it?

A A branch, because it makes a decision

B A loop, because it repeats

3. Read this step: 'REPEAT 5 times: bounce the ball'. What is it?

A A loop, because it repeats steps

B A branch, because it makes a choice

4. Which sentence is true about most algorithms?

A They can only use one of these at a time

B They often mix sequence, branches and loops

5. An algorithm says: 1. Get out your bag. 2. REPEAT UNTIL the bag is full: add a book. 3. Zip up the bag. Which part is the loop?

A Step 2, because it repeats until the bag is full

B Step 3, because it comes last

Match the Pairs

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

Left column		Right column
11. Get the bowl 2. Pour in the cereal		AThis is a loop, not a branch. It repeats a step until a condition is true. It does not choose between paths.
2REPEAT 5 TIMES: Kick the ball		BIF it is raining THEN take an umbrella ELSE wear a hat
3A branch is a decision that picks which steps to follow		CSteps done in order ARE a sequence. Every algorithm has a sequence, even when it also has branches and loops.
4An algorithm can mix all three parts: a sequence, a branch and a loop		DA sequence: steps done one after the other in order
5REPEAT UNTIL the bin is full: Put in a bottle (labelled as a branch)		EA loop: a step that is repeated more than once
6Steps 1, 2 and 3 are all done in order, so this algorithm has no sequence		F1. Open the gate 2. REPEAT 3 TIMES: IF dog is hungry THEN feed it

Definitions

sequence, branch, loop

Fill in the Blanks

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

walk to the door __ the door is shut THEN open the door

______ 10 TIMES IF the cup is empty THEN fill the cup

REPEAT UNTIL the bag is full IF the apple is ripe ____ pick the apple

IF it is raining THEN take an umbrella ____ wear a cap

Step 1: wake up // sequence REPEAT 3 TIMES // ____ IF tired THEN sleep // branch

Spot the Error

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

Question 1

A SET claps TO 0

B IF 5 TIMES

C ADD 1 TO claps

D END REPEAT

E SHOW claps

Question 2

A ASK for the user's age

B IF age < 13 THEN

C SHOW 'You can join'

D ELSE

E SHOW 'You can join'

Question 3

A IF it is dark

B TURN ON the light

C ELSE

D TURN OFF the light

Question 4

A REPEAT 3 TIMES

B IF cup is full THEN

C FILL the cup

D END IF

E END REPEAT

Question 5

A FILL the kettle with water

B SWITCH ON the kettle

C SWITCH OFF the kettle

D POUR water into the cup

Answer Key

Algorithms that use sequence, branching and iteration together

Section A: Quick Questions

B — Steps that happen one after another in order

A — A branch, because it makes a decision

A — A loop, because it repeats steps

B — They often mix sequence, branches and loops

A — Step 2, because it repeats until the bag is full

Section B: Match the Pairs

1. Get the bowl 2. Pour in the cereal → A sequence: steps done one after the other in order

REPEAT 5 TIMES: Kick the ball → A loop: a step that is repeated more than once

A branch is a decision that picks which steps to follow → IF it is raining THEN take an umbrella ELSE wear a hat

An algorithm can mix all three parts: a sequence, a branch and a loop → 1. Open the gate 2. REPEAT 3 TIMES: IF dog is hungry THEN feed it

REPEAT UNTIL the bin is full: Put in a bottle (labelled as a branch) → This is a loop, not a branch. It repeats a step until a condition is true. It does not choose between paths.

Steps 1, 2 and 3 are all done in order, so this algorithm has no sequence → Steps done in order ARE a sequence. Every algorithm has a sequence, even when it also has branches and loops.

Section C: Definitions

sequence, branch, loop — Most algorithms mix steps in order (sequence), decisions (branch) and repeats (loop). When you read an algorithm, you can label each part and explain it in your own words.

Section D: Fill in the Blanks

walk to the door
IF the door is shut THEN
  open the door

REPEAT 10 TIMES
  IF the cup is empty THEN
    fill the cup

REPEAT UNTIL the bag is full
  IF the apple is ripe THEN
    pick the apple

IF it is raining THEN
  take an umbrella
ELSE wear a cap

Step 1: wake up // sequence
REPEAT 3 TIMES // loop
IF tired THEN sleep // branch

Section E: Spot the Error

B — The loop must start with REPEAT, not IF. IF is for a decision (branch). It should be REPEAT 5 TIMES so it matches END REPEAT.

C — This branch runs when the age is under 13, so it should show 'Ask a parent first'. 'You can join' belongs in the ELSE branch.

A — Every IF decision needs the word THEN after the condition. It should be IF it is dark THEN.

B — The branch should only fill the cup when it is empty. Filling a full cup makes no sense. It should be IF cup is empty THEN.

C — In a sequence the order matters. The kettle must stay on and the algorithm must wait until the water boils. The line should be WAIT UNTIL water boils.