Introducing Loops: Repeating Actions

Active learning works because loops become tangible when students physically repeat actions or see immediate visual results. Hands-on activities let students experience the efficiency of loops over manual repetition, building both understanding and confidence in programming concepts.

• Year 3
• Computing
• 4 activities
• 20 min–40 min

Learning Objectives

1. Compare the efficiency of a program using a loop versus one with repeated code blocks for drawing a pattern.
2. Construct a program using a loop block to create a repeating visual pattern with a sprite.
3. Explain the function of a loop in simplifying repetitive programming tasks.
4. Identify the number of repetitions required for a specific repeating pattern in a sprite program.

Collaborative Problem-Solving

⏱ 20 min·Small Groups

Unplugged Demo: Human Loops

Students stand in a circle and perform actions like clapping or jumping. Teacher introduces a leader who says 'repeat 5 times: clap, jump'. Groups practise giving and following loop instructions, then discuss efficiency over manual repeats. Transition to block code examples on the board.

Prepare & details

Explain the purpose of a loop in programming.

Facilitation Tip: During the Human Loops activity, position students in a circle to physically act out loop iterations so everyone sees how repetition is structured and controlled.

Setup: Groups at tables with problem materials

Materials: Problem packet, Role cards (facilitator, recorder, timekeeper, reporter), Problem-solving protocol sheet, Solution evaluation rubric

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 30 min·Pairs

Block Coding: Square Patterns

In Scratch or similar, students drag 'repeat 4' blocks around move and turn commands to draw squares. They test, adjust angles for perfect shapes, and add colours. Pairs challenge each other to create stars or houses with loops.

Prepare & details

Compare using a loop to repeating the same block multiple times.

Facilitation Tip: After introducing block coding for squares, ask students to predict what happens if the repeat number changes before they run the program, reinforcing cause and effect.

Setup: Groups at tables with problem materials

Materials: Problem packet, Role cards (facilitator, recorder, timekeeper, reporter), Problem-solving protocol sheet, Solution evaluation rubric

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 40 min·Small Groups

Loop Challenges Relay

Set up stations with task cards: repeat to draw circles, move in patterns, or animate sprites. Small groups complete one per station, passing iPads. Debrief as whole class on successes and loop benefits.

Prepare & details

Construct a program that uses a loop to draw a repeating pattern.

Facilitation Tip: During Loop Challenges Relay, have teams swap completed challenges and peer-assess loop structures and outputs to build collaborative debugging skills.

Setup: Groups at tables with problem materials

Materials: Problem packet, Role cards (facilitator, recorder, timekeeper, reporter), Problem-solving protocol sheet, Solution evaluation rubric

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Collaborative Problem-Solving

⏱ 25 min·Pairs

Debug and Remix

Provide starter programs with loop errors, like infinite repeats or misplaced blocks. Students fix in pairs, then remix a classmate's working program to add new looped actions. Share one remixed version with the class.

Prepare & details

Explain the purpose of a loop in programming.

Setup: Groups at tables with problem materials

Materials: Problem packet, Role cards (facilitator, recorder, timekeeper, reporter), Problem-solving protocol sheet, Solution evaluation rubric

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Teaching This Topic

Teach loops by starting with physical movement to connect abstraction to real-world actions. Avoid explaining loops theoretically; instead, let students discover their power through doing. Research shows that students grasp repetition best when they first experience it unplugged before moving to block coding, so build from concrete to abstract to support long-term retention.

What to Expect

Students will confidently use loops to repeat actions without error, explain why loops simplify code, and adjust loop counts to change program outcomes. They will compare looped and non-looped code to recognize efficiency and debugging advantages.

Watch Out for These Misconceptions

Common Misconception

During Human Loops, watch for students who act out loops indefinitely without stopping after the set count. Redirect by timing each iteration and stopping after the agreed repeat number.

What to Teach Instead

During Block Coding: Square Patterns, have students adjust the repeat number and observe the program end exactly at that count, proving loops stop when instructed. Encourage them to verbalize the stop condition to reinforce understanding.

Common Misconception

During Loop Challenges Relay, listen for students who assume loops can only repeat identical actions inside them. Redirect by asking teams to modify one action inside the loop to create variation.

What to Teach Instead

During Debug and Remix, guide students to identify that loops can contain different commands by analyzing how a loop with a 'move' and a 'change color' block creates a varied pattern. Discuss how this flexibility makes loops powerful.

Common Misconception

During Block Coding: Square Patterns, watch for students who manually repeat code instead of using loops despite instruction. Ask them to compare the length of their manual code with a peer’s looped version side by side.

What to Teach Instead

During Loop Challenges Relay, have students edit both manual and looped versions of a pattern to change the repeat count, highlighting the time and error savings loops provide when modifying programs.

Assessment Ideas

Exit Ticket

After Block Coding: Square Patterns, provide two code snippets: one with manual repeats and one using a 'repeat 4' loop. Ask students to circle the more efficient code and write one sentence explaining their choice.

Quick Check

During Loop Challenges Relay, display a simple repeating pattern (e.g., a sprite drawing a triangle five times). Ask students to identify the action to be repeated and the number of repeats needed, then share answers with their team before moving on.

Discussion Prompt

After the Unplugged Demo: Human Loops, pose the question: 'If you need a sprite to say 'Hello!' ten times, would you drag out ten separate 'say' blocks or use a loop? Explain your choice to a partner, focusing on how loops make changes easier.'

Extensions & Scaffolding

• Challenge students to create nested loops that draw increasingly complex geometric patterns in Scratch.
• Scaffolding: Provide a partially completed loop structure with missing blocks for students to fill in, focusing on the repeat count and actions inside.
• Deeper exploration: Introduce variables inside loops to create patterns that change slightly with each iteration, such as growing shapes or alternating colors.

Key Vocabulary

Loop	A programming structure that repeats a sequence of instructions a specified number of times or until a condition is met.
Repeat block	A specific code block, often found in visual programming languages, that encloses other blocks to execute them multiple times.
Iteration	One complete cycle or pass through the instructions within a loop.
Sprite	A small character or graphic object on the screen that can be moved and programmed to perform actions.