Count-controlled iteration
Lesson details
Learning outcome
I can use count-controlled iteration to repeat a sequence of commands a set number of times.
Key learning points
- Iteration can be used to repeat sequences of commands in a program.
- Condition-controlled iteration will execute until a condition is met or is no longer met.
- Count-controlled iteration will execute a set number of times.
Keywords
Iteration - the process of repeating a sequence of instructions within a program loop
Count-controlled - a command that repeatedly runs a sequence of instructions a predefined number of times
Condition-controlled - a command that repeatedly runs a sequence of instructions until a condition is no longer being met
Common misconception
Iteration means a program will repeat something a set number of times.
Count-controlled iteration will repeat a sequence of commands a set number of times. Condition-controlled iteration will repeat a sequence of commands until a condition is met and so the number of times it will repeat can never be predicted.
Teacher tip
The solution for Task B requires a variable to be decreased by 1 each time the loop is executed. Explore this with pupils by using a number of props in a container and providing a visualisation of removing an item during each iteration.
Equipment
Pupils will need access to a device with block-based programming software. Examples in this lesson use Scratch https://oak.link/scratch
Licence
Lesson video
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Prior knowledge starter quiz
6 Questions
Q1.What will be output when this program is executed?
Q2.What will be output when this program is executed?
Q3.Which conditions would evaluate as True with the following inputs?
Q4.=, < and > are all...
Q5.and, or and not are all...
Q6.Match the logic operator to the correct description.
True when both values are True
True when either or both values are True
True when the value is False
Assessment exit quiz
4 Questions
Q1.Match the keyword to the correct description.
repeatedly runs a sequence of instructions a set number of times
repeatedly runs a sequence of instructions until a condition is met
Q2.Iteration can make a program more , rather than having to have lots of duplicate blocks.
Q3.Which block is used in Scratch for iteration?
Q4.What will this code block do?
To help you plan your 7 computing lesson on: Count-controlled iteration, download all teaching resources for free and adapt to suit your pupils' needs...
To help you plan your 7 computing lesson on: Count-controlled iteration, download all teaching resources for free and adapt to suit your pupils' needs.
The starter quiz will activate and check your pupils' prior knowledge, with versions available both with and without answers in PDF format.
We use learning cycles to break down learning into key concepts or ideas linked to the learning outcome. Each learning cycle features explanations with checks for understanding and practice tasks with feedback. All of this is found in our slide decks, ready for you to download and edit. The practice tasks are also available as printable worksheets and some lessons have additional materials with extra material you might need for teaching the lesson.
The assessment exit quiz will test your pupils' understanding of the key learning points.
Our video is a tool for planning, showing how other teachers might teach the lesson, offering helpful tips, modelled explanations and inspiration for your own delivery in the classroom. Plus, you can set it as homework or revision for pupils and keep their learning on track by sharing an online pupil version of this lesson.
Explore more key stage 3 computing lessons from the Using fundamental programming constructs in a block-based language unit, dive into the full secondary computing curriculum, or learn more about lesson planning.