Iteration: repeating steps

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Quick Questions

Shade in the A or B circle for each question.

1. Which one is an example of iteration?

A Doing each step once and then stopping

B Repeating the same steps instead of writing them out again

2. You write: clap, clap, clap, clap, clap. How could you write this with iteration?

A REPEAT 5 TIMES: clap

B clap 5 TIMES REPEAT

3. Why do programmers use loops?

A Loops save effort because we don't write the same steps again and again

B Loops make a computer forget the steps it already did

4. The steps that get repeated inside a loop are called the...

A loop ending

B loop body

5. Which list of steps has a repeated pattern you could turn into a loop?

A step forward, turn, step forward, turn, step forward, turn

B wake up, eat breakfast, brush teeth, catch the bus

Match the Pairs

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

Left column		Right column
1REPEAT 4 TIMES		AThe loop body is not clearly shown. The steps to repeat should be indented under REPEAT so we know which steps are in the loop.
2REPEAT 3 TIMES clap		BThe loop body is the clap step, because it is the part that gets repeated
3Loops save effort: one loop does the work of writing the same steps many times		CIteration: the steps inside are repeated 4 times, so you don't write them out four times
4Spotting repeated steps: the same steps appear over and over, so they can go in a loop		DThe same step is written out again and again. A loop like REPEAT 5 TIMES with wave inside would save effort.
5REPEAT 3 TIMES clap stomp		Estep forward step forward step forward
6wave wave wave wave wave		FREPEAT 5 TIMES jump

Definitions

iteration

Fill in the Blanks

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

______ 4 TIMES clap END REPEAT

// Stomp 5 times REPEAT _ TIMES stomp

// Clap 3 times REPEAT 3 TIMES ____

REPEAT 6 _____ jump END REPEAT

REPEAT 3 TIMES spin END ______

Spot the Error

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

Question 1

A REPEAT TIMES

B Move forward 10

C Turn right 90

D END REPEAT

Question 2

A Pick up the toothbrush

B REPLAY 10 TIMES

C Brush one tooth

D END REPEAT

E Rinse your mouth

Question 3

A Get a skipping rope

B REPEAT 20 TIMES

C Jump over the rope

D STOP REPEAT

E Put the rope away

Question 4

A Collect the blocks

B REPEAT 8 TIMES

C Knock the tower down

D END REPEAT

Question 5

A # Draw a triangle

B REPEAT 4 TIMES

C Move forward 50

D Turn right 120

E END REPEAT

Answer Key

Iteration: repeating steps

Section A: Quick Questions

B — Repeating the same steps instead of writing them out again

A — REPEAT 5 TIMES: clap

A — Loops save effort because we don't write the same steps again and again

B — loop body

A — step forward, turn, step forward, turn, step forward, turn

Section B: Match the Pairs

REPEAT 4 TIMES → Iteration: the steps inside are repeated 4 times, so you don't write them out four times

REPEAT 3 TIMES clap → The loop body is the clap step, because it is the part that gets repeated

Loops save effort: one loop does the work of writing the same steps many times → REPEAT 5 TIMES jump

Spotting repeated steps: the same steps appear over and over, so they can go in a loop → step forward step forward step forward

REPEAT 3 TIMES clap stomp → The loop body is not clearly shown. The steps to repeat should be indented under REPEAT so we know which steps are in the loop.

wave wave wave wave wave → The same step is written out again and again. A loop like REPEAT 5 TIMES with wave inside would save effort.

Section C: Definitions

iteration — Repeating a set of steps instead of writing them out again and again. The repeated steps are called the loop body. Loops save effort.

Section D: Fill in the Blanks

REPEAT 4 TIMES
  clap
END REPEAT

// Stomp 5 times
REPEAT 5 TIMES
  stomp

// Clap 3 times
REPEAT 3 TIMES
  clap

REPEAT 6 TIMES
  jump
END REPEAT

REPEAT 3 TIMES
  spin
END REPEAT

Section E: Spot the Error

A — A loop must say how many times to repeat. The first line should be REPEAT 4 TIMES so the loop body runs 4 times.

B — The keyword that starts a loop is REPEAT, not REPLAY. It should be REPEAT 10 TIMES.

D — The loop body must be closed with END REPEAT. STOP REPEAT is not the right ending, so line 4 should be END REPEAT.

C — The loop body is the step that gets repeated, and it should help build the tower. Line 3 should be Stack one block, not knocking the tower down.

B — A triangle has 3 sides, so the loop body must repeat 3 times. Repeating 4 times would draw too much. It should be REPEAT 3 TIMES.