National 5 Computing Science revision: every topic in one place

National 5 Computing Science: Start here

This is the whole of National 5 Computing Science on one page. For each topic you will find what you need to be able to do, written as a checklist you can tick off. Topics with a free guide link to it. Use the page to find your gaps, then practise questions on those topics.

The course has two parts that everyone does, software design and development and computer systems, then one more part chosen by your school: database design and development or web design and development. New to the exam itself? Start with how to prepare for the National 5 Computing Science exam.

Software design and development

This is the biggest part of the paper. Most of it is about reading, writing and fixing code in SQA reference language, the plain-English pseudocode used in the exam. You can usually answer in a language you know, such as Python.

Iterative development. Name the stages: analysis, design, implementation, testing, documentation, evaluation. Explain why you might go back to an earlier stage, with a real example such as testing finding a mistake in the design. See describing going back.
Purpose and functional requirements. Say what a program is for, and list its inputs, processes and outputs.
Design. Choose the right data type or structure for a problem. Read and complete structure diagrams, flowcharts and pseudocode. Sketch a wireframe showing inputs and outputs. Choosing the most suitable data type covers the traps.
Data types and structures. Character, string, integer, real, Boolean and 1-D arrays, and when to use each.
Assignment and arithmetic, and joining strings. Store values, use + - * / and exponentiation, and join strings together (concatenation).
Selection. IF statements with simple conditions and with AND, OR and NOT.
Iteration. Fixed loops (a set number of times) and conditional loops (until something happens).
Predefined functions. Use round, random and length, with the right parameters. Writing the whole call shows what the marks are for.
Standard algorithms. Input validation, a running total inside a loop, and traversing a 1-D array. These are asked again and again: see input validation and running total within a loop.
Testing. Pick normal, extreme and exceptional test data, fill in a test table, and recognise syntax, execution and logic errors. See test data and test tables.
Evaluation. Judge a program on fitness for purpose, efficient use of constructs, robustness and readability. Examiners want answers about the code in front of you: evaluating a program explains how.

Computer systems

This part has no programming, but it has calculations. Practise them until the steps are automatic, because they are marks you can be sure of.

Binary integers. Convert positive whole numbers between binary and denary.
Floating point. Show a positive real number as a mantissa and an exponent.
Extended ASCII. How characters are stored as 8-bit codes.
Graphics. Vector graphics (objects such as rectangles, ellipses, lines and polygons with attributes) compared with bit-mapped graphics.
Computer architecture. The processor (registers, ALU and control unit), memory locations with addresses, and the data and address buses. See inside the processor.
Interpreters and compilers. Why high-level code has to be translated, and how the two translators differ. Spotting the clues shows how the exam asks.
Energy and the environment. How the way we use computers affects energy use: monitor settings, power-down settings and standby.
Security. What firewalls do and how encryption protects data sent between computers.

Database design and development

One of the two choices for the last part of the paper. If your class studied databases, it is worth 25 marks.

Requirements. Tell end-user requirements from functional requirements. This guide explains why repeating the question does not gain the mark.
UK GDPR. The principles for handling personal data, and what they mean for a database.
Design. Draw an entity-relationship diagram for two entities, complete a data dictionary (keys, types, sizes, validation) and design a query with its fields, tables, criteria and sort order.
A relational database. Two linked tables and referential integrity. Explaining it for the mark shows what a full answer says.
SQL. SELECT with FROM, WHERE and ORDER BY, plus INSERT, UPDATE, DELETE and an equi-join between two tables. Start with SQL with two tables and UPDATE and INSERT.
Testing and evaluation. Predict what an SQL statement will output, compare it with what it does, and judge a database for fitness for purpose and accuracy.

Web design and development

The other choice, also worth 25 marks. Skills in HTML and CSS are tested both in the paper and in the assignment.

Requirements. End-user and functional requirements for a website. The requirements guide covers both databases and websites.
Design. Plan a site structure (a home page and linked pages), draw a wireframe, and make a paper prototype. Know what copyright law means for text, graphics, video and audio.
File formats. Compare WAV and MP3, and JPEG, GIF and PNG, and explain why compression is needed. Making a sound file smaller is a common question.
HTML. Write and read the standard tags, including links, images, audio, video and lists. Absolute and relative addresses is a frequent loser of marks.
CSS. Style elements, classes and IDs, in internal and external style sheets. See CSS classes and external style sheets.
JavaScript. The mouse events onmouseover and onmouseout.
Testing and evaluation. Check that a site matches its design, that links work and that media display, then judge it for fitness for purpose.

How to use this page

Go through each list and be honest: can you do it without notes? Mark the ones you cannot.
For each gap, answer a few exam-style questions before you read the notes again. A wrong answer shows you exactly what to fix.
Come back to the whole list every couple of weeks. The topics you can do today are the ones you will lose if you stop practising them.

The course on this site has a short note, a simulation and a practice quiz for every topic in these lists, so you can work down the page.

The full course covers every topic like this. Every topic in National 5 Computing Science has a short note, a simulation to try and a practice quiz with feedback on every answer, plus coding lessons, a full mock exam and a progress report for parents.

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This site is independent: it is not connected to the SQA or Qualifications Scotland. Points from the examiners' course reports are given in our own words.