Computing KS2: Algorithms

This short film for primary schools outlines how algorithms are sets of instructions to make something happen, before explaining further using a recipe analogy.

The film outlines how algorithms are the starting points for computer programs that solve problems.

It then looks at the example of using an electronic card key to open a door, using a flow diagram to organise the instructions and steps needed to make sure the door only unlocks when the correct card key is used.

The film finishes with more examples of how algorithms are used in computer-based tools and systems like social media feeds and search engine rankings.

This short film is from the BBC Teach series, Cracking Computing.

Teacher Notes

A good way to introduce the idea of algorithms is to focus on familiar lists of instructions that organise everyday life - for example, taking the register, getting ready for a school lesson, packing up at the end of the day - and turning them into flow charts.

The next step is to explore problems or dilemmas that include a question, and create a list of instructions or statements that solve the problem. Again, flow charts can be used to clarify the steps and sequence lists for pupils.

It is important that, before pupils start to write a program to solve a problem or achieve a specific outcome, they have a clear idea of what they want the program to achieve, in the form of an algorithm, either as a flow chart or list of instructions.
For example, when programming a computer game character the algorithm might look like this:

  • When left arrow clicked character moves left 10 steps
  • When right arrow clicked character moves right 10 steps
  • When space bar clicked character jumps up

Other subjects

English: Understanding algorithms fits well with work on instruction writing, or explanation texts that explain a process or sequence of events. Similar vocabulary is used: for example, firstly, then, when, next, finally, etc.

Maths: In Maths the word algorithm is used to describe the series of steps carried out to complete a calculation or solve a problem. For example, to solve 3 x 7 we need to carry out the following steps:

  • Start with zero
  • Add 7
  • Add 7 to the new total
  • Add 7 to the new total

Curriculum Notes

This short film is suitable for teaching:

  • KS2 computing curriculum in England
  • Technologies curriculum area at 2nd Level in Scotland
  • KS2 digital competence framework in Wales
  • KS2 using ICT cross-curricular skill in Northern Ireland

More from Cracking Computing

Computer networks
Creating with computing
Input and output
Logical reasoning
Search technologies
Working with data