Loops for Repetition

Active learning helps students grasp loops for repetition because they immediately see how repeating code blocks saves time and reduces errors. When students build, test, and debug their own projects, they experience firsthand why fixed loops and repeat-until loops behave differently.

• Year 5
• Computing
• 4 activities
• 25 min–45 min

Learning Objectives

1. Design a program using a fixed loop to draw a repeating geometric pattern.
2. Compare the functionality and use cases of 'repeat a number of times' loops versus 'repeat until' loops.
3. Explain the efficiency benefits of using loops compared to sequential code for repetitive tasks.
4. Analyze the output of a given program to identify the type and parameters of the loop used.

Project-Based Learning

⏱ 30 min·Pairs

Pair Programming: Pattern Builder

Pairs use Scratch to draw a repeating pattern of shapes with a 'repeat' block. One partner adds code while the other suggests loop counts and predicts outcomes. They test, adjust the repeat number, and explain efficiency gains to the class.

Prepare & details

Explain the benefit of using a loop instead of writing the same code multiple times.

Facilitation Tip: During Pair Programming: Pattern Builder, circulate and ask each pair to verbalize their loop structure before coding to reinforce planning.

Setup: Flexible workspace with access to materials and technology

Materials: Project brief with driving question, Planning template and timeline, Rubric with milestones, Presentation materials

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

Project-Based Learning

⏱ 45 min·Small Groups

Small Groups: Loop Type Challenges

Groups tackle three tasks: fixed repeat for a spiral, repeat until a sprite touches an edge, and mixed loops for a game animation. They record differences in a shared document and present one demo.

Prepare & details

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

Facilitation Tip: In Small Groups: Loop Type Challenges, give each group one loop snippet to test and swap it with another group after 5 minutes to broaden perspective.

Setup: Flexible workspace with access to materials and technology

Materials: Project brief with driving question, Planning template and timeline, Rubric with milestones, Presentation materials

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

Project-Based Learning

⏱ 25 min·Whole Class

Whole Class: Debug Relay

Display buggy looped code on the board. Class calls out fixes in turns, teacher inputs changes, and all predict results before running. Vote on best solutions and discuss why loops failed.

Prepare & details

Compare 'repeat until' loops with 'repeat a number of times' loops.

Facilitation Tip: For Whole Class: Debug Relay, assign roles so every student participates, such as reader, typist, and observer to keep everyone engaged.

Setup: Flexible workspace with access to materials and technology

Materials: Project brief with driving question, Planning template and timeline, Rubric with milestones, Presentation materials

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

Project-Based Learning

⏱ 35 min·Individual

Individual: Custom Loop Design

Pupils design a program with loops for a personal pattern, like a flower or path. They write steps first, code independently, then share screenshots in a class gallery for peer feedback.

Prepare & details

Explain the benefit of using a loop instead of writing the same code multiple times.

Facilitation Tip: During Individual: Custom Loop Design, provide printed loop templates for students to annotate before coding to support planning.

Setup: Flexible workspace with access to materials and technology

Materials: Project brief with driving question, Planning template and timeline, Rubric with milestones, Presentation materials

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

Teaching This Topic

Teach loops by having students compare fixed and condition-based loops in the same project. Model how to trace loop execution step-by-step on the board so students see how the loop counter or condition changes each cycle. Avoid jumping straight to abstract explanations; let students observe the loop’s effect through visible outputs like sprites drawing shapes.

What to Expect

Students will confidently use repeat times and repeat until loops to create patterns and solve simple tasks. They will explain the difference between the two loop types and justify their choice based on the task requirements.

Watch Out for These Misconceptions

Common Misconception

During Pair Programming: Pattern Builder, watch for students assuming all loops run forever.

What to Teach Instead

Ask pairs to test their fixed loop by setting the count to 3 and observing that it stops, then adjust the repeat until loop to use a simple condition like touching a color edge to see it stops when met.

Common Misconception

During Small Groups: Loop Type Challenges, watch for students treating repeat until the same as repeat times.

What to Teach Instead

Have groups run identical tasks with both loop types and note when each loop stops, highlighting that repeat until depends on a condition while repeat times always runs the set number.

Common Misconception

During Whole Class: Debug Relay, watch for students thinking loops only save time on very long repetitions.

What to Teach Instead

After debugging, demonstrate how changing loop counts from 10 to 5 or 100 to 10 shows code remains clean and easy to adjust, reinforcing efficiency even for short tasks.

Assessment Ideas

Exit Ticket

After Pair Programming: Pattern Builder, give students a Scratch project with a sprite drawing a square using a fixed loop. Ask them to answer how many times the loop repeats, what happens if changed to 5, and why the loop was useful in one sentence.

Quick Check

During Small Groups: Loop Type Challenges, display two code snippets side-by-side: one fixed loop drawing 5 circles, one repeat until loop stopping when a sprite reaches a certain X-coordinate. Ask students to identify which is which and explain one scenario where the other type would be better.

Discussion Prompt

After Whole Class: Debug Relay, pose the question: 'Would you use a fixed loop or a repeat until loop to print numbers 1 to 100? Explain why and how it’s better than writing each print statement separately.'

Extensions & Scaffolding

• Challenge: Ask students to design a program that draws a spiral pattern using nested loops.
• Scaffolding: Provide a partially completed Scratch project with a loop structure already set up.
• Deeper exploration: Introduce a loop that changes its count based on user input, such as drawing a starburst with a variable number of points.

Key Vocabulary

Loop	A control flow statement that allows code to be executed repeatedly. It saves time and effort by avoiding the need to write the same code multiple times.
Iteration	A single execution of the code block within a loop. Each time the loop runs, it completes one iteration.
Fixed Loop	A loop that repeats a specific number of times, such as 'repeat 10 times'. The number of repetitions is known before the loop starts.
Condition-Controlled Loop	A loop that continues to repeat as long as a certain condition is true, or until a specific condition is met (e.g., 'repeat until touching edge').