That Blue Square Thing

Computer Science GCSE

Note: this page deals with the old Edexcel GCSE (grades A-G) which no longer exists. I'm keeping it as an archive and because a number of the resources will still apply to newer (grades 1-9) courses. The AQA GCSE CompSci pages deal with a current course.


Algorithms show exactly how a task can be completed. Technically they are a sequence of step by step, unambiguous instructions for solving a particular problem.

You need to be able to read (and understand) and write algorithms written in:

In an exam you may have to write an algorithm as well as read one. The key here os getting the logic right, not necessarily writing with perfect syntax. So, it's important to know what pseudo code commands mean, but it's not essential to write perfect pseudo code.

It is important to be able to draw a proper flowchart however, so make sure you know the symbols to use.

PDF iconAlgorithm basics - PDF of a powerpoint used in class

PDF iconFlowchart symbols - just the slide with the symbols on

PDF iconAlgorithm Programming Constructs - an important set of key programming concepts and constructs and how they are developed in algorithms. You should have implemented all of these ideas using Python, but it's important to understand that they are key ideas in programming and know how they can be applied in non-program code algorithms.

There are videos which develop the key ideas of sequence, selection and repeition (or iteration) on the BBC Bitesize websitewiki link.

Questions using algorithms

There are more algorithm questions on the exam prep page for now. I might move those here as well at some point.

PDF iconMaths Game question - exam style question using a flowchart algorithm

PDF iconBank Balance Question - exam style question using structured English logic

PDF iconIPO Question - exam style question using a pseudo code algorithm

Pseudo Code

There are a core set of pseudo code commands that you need to be able to understand.

PDF iconPseudocode commands - a summary of key pseudo code reserved words - needed for the exam

PDF iconFunctions in pseudo code - for the exam

There are some fairly useful bits and pieces on the BBC Bitesize website about algorithmswiki link. Pages 1, 2, 4 and 5 are the most useful at this point.

The Bitesize pages on algorithms and control flowwiki link are also useful - especially when dealing with sequence, selection and repetition. There are videos which might be helpful.

Note that you need to know some specific algorithms, but I won't cover those until Year 11.