Lesson 4: Algorithm design

Pupils create a game in Scratch using the remaining pillar of computational thinking - algorithm design

Before the lesson

Download classroom resources

Learning objective

  • To understand how to create an algorithm and what it can be used for

National curriculum

Pupils should be taught to:

  • Design, write and debug programs that accomplish specific goals, including controlling or simulating physical systems; solve problems by decomposing them into smaller parts
  • Use logical reasoning to explain how some simple algorithms work and to detect and correct errors in algorithms and programs

Success criteria

Cross-curricular links

Attention grabber

Main event


Pupils needing extra support: Provide the Activity: Code blocks needed for drawing the square – but put them in the wrong order for pupils to sequence correctly.


Pupils working at greater depth: Show the ‘Hour of Code Frozen’ activity, which uses the same concept to draw a selection of different shapes and snowflakes, asking them to predict what will happen and justify these predictions.

Wrapping up

Assessing pupils' progress and understanding


Created by:
Cat Lamin,  
Computing specialist
Cat was a committed primary school teacher for twelve years. After starting her independent consultancy ‘Crossover Solutions’ she has travelled to Argentina, Brazil and America to share her wealth of knowledge of computer science with other teachers. Her enjoyment for…
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