AQA A-Level Computer Science Active Recall Guide (7517)

AQA · A-Level

AQA A-Level Computer Science Active Recall Guide

A question-and-answer revision guide for AQA A-Level Computer Science, built to be worked in three passes rather than read.

AQA
A-Level
Specification 7517
13 topics

See what is inside or try the sample questions.

AQA A-Level Computer Science Active Recall Guide cover

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The 3-step active recall method

Re-reading notes is a futile process when your aim is to remember the information and successfully apply it in exam settings. Active recall is the method you use to ensure the information sticks for a long period of time. But even active recall can be futile unless you have a structured way of implementing it. This is where the 3-step active recall method comes in, a structured method that is signature to the Levo Learning guides.

Step 1
Answer up to 10 questions cold, closed book, even if you are unsure on the topic.
Step 2
Answer the same questions again, but open book. Write the correct answer down even if it seems pointless.
Step 3
Repeat as step 1 and answer the questions closed book again.

Worked across the AQA A-Level Computer Science specification, one subtopic at a time.

The subject, and what is assessed

AQA A-Level Computer Science (specification 7517) is assessed by two equally weighted written and on-screen exams and a practical programming project. Paper 1 is sat on screen and tests the ability to program alongside data structures, algorithms and the theory of computation. Paper 2 is a written paper covering data representation, computer systems, architecture, networking, databases, Big Data and functional programming. The non-exam assessment is a programming project worth a fifth of the qualification.

Paper	Covers	Length	Marks	Weighting
Paper 1	On-screen exam	2 hours 30 minutes	100 marks	40%
Paper 2	Written exam	2 hours 30 minutes	100 marks	40%
Non-exam assessment	The computing practical project		75 marks	20%

Memorisation, then application

Marks are given for applying content to the question that has been set, which cannot happen while the content is still being looked up. Step 1 shows what is actually held. Step 2 puts the correct wording in front of you while the gap is still fresh. Step 3 repeats the cold test, and the difference between the first and third attempt is the part that has moved.

Every question in the guide is paired with its answer in the same document, so step 2 is done from the guide itself rather than from a separate set of notes.

What is inside the guide

Questions are grouped by topic and then by subtopic, following the AQA specification. Open a topic to see its subtopics.

Fundamentals of Programming12 subtopics

Data types, the statement types every imperative language is built from, subroutines and parameters, scope and stack frames, recursion, and the procedural and object-oriented paradigms. Examined on Paper 1.

Data types19
Programming concepts and program structure17
Arithmetic operations15
Relational Operations, Constants and Variables20
String-handling operations19
Random numbers and exception handling10
Subroutines, parameters and return values16
Variable scope and stack frames15
Recursive techniques12
Programming paradigms and the procedural approach12
Classes, Objects and Instantiation17
Aggregation, Composition and Class Diagrams17

Fundamentals of Data Structures11 subtopics

Arrays, records and files, then the abstract data types, stacks, queues, graphs, trees, hash tables and dictionaries, with the operations and traces each is examined through. Examined on Paper 1.

Data Structures and Abstract Data Types17
Static and Dynamic Data Structures10
Queues and Linear Queues11
Circular and Priority Queues10
Stacks12
Graphs16
Trees13
Hash tables12
Dictionaries9
Vectors and Their Notation10
Vector Arithmetic and Geometry16

Fundamentals of Algorithms6 subtopics

Graph and tree traversal, Reverse Polish notation, searching, sorting and Dijkstra's shortest path algorithm, each with the time complexity it is judged by. Examined on Paper 1.

Graph traversal12
Tree traversal15
Reverse Polish notation12
Searching algorithms18
Sorting algorithms16
Optimisation algorithms9

Theory of Computation16 subtopics

Abstraction and decomposition, finite state machines, regular expressions, Backus-Naur Form, Big-O complexity, tractability, the Halting problem and Turing machines. Examined on Paper 1.

Boolean Expressions and De Morgan's Laws12
Iteration, Pseudo-Code and Hand-Tracing13
Abstraction by Representation and Generalisation11
Procedural and Functional Abstraction9
Data Abstraction and Problem Reduction8
Decomposition and Composition8
Automation and Finite State Machines18
Sets and Set Notation16
Subsets and Set Operations8
Regular expressions and regular languages14
Backus-Naur Form and syntax diagrams12
Comparing Algorithms and Functions20
Order of complexity and Big-O notation15
Limits of computation, tractability and heuristics9
Computable problems and the Halting problem8
Turing machines14

Fundamentals of Data Representation16 subtopics

Number bases and binary arithmetic, two's complement, fixed and floating point, rounding error, character codes, error checking, images, sound and encryption. Examined on Paper 2.

Number systems and the sets of numbers16
Number bases: decimal, binary and hexadecimal20
Bits, bytes and units of information15
Unsigned binary and binary arithmetic15
Signed binary using two's complement16
Fixed point and floating point representation18
Normalisation of floating point numbers11
Rounding errors, accuracy, range and precision19
Character coding systems10
Error checking and correction16
Bit patterns, analogue and digital11
Bitmapped graphics13
Vector graphics12
Digital representation of sound12
MIDI and Data Compression18
Encryption18

Fundamentals of Computer Systems8 subtopics

Hardware and software and how software is classified, programming languages and their translators, logic gates and Boolean algebra. Examined on Paper 2.

Hardware, Software and Its Classification13
System Software and the Operating System11
Translators and the Role of the Operating System10
Classification of programming languages14
Types of program translator16
Logic Gates and Their Truth Tables12
Building and Reading Logic Circuits20
Boolean algebra18

Fundamentals of Computer Organisation and Architecture11 subtopics

The stored program concept, the processor and its registers, the Fetch-Execute cycle, instruction sets and addressing modes, interrupts, performance factors, and input, output and storage devices. Examined on Paper 2.

Internal hardware components and buses17
The Stored Program Concept and the Processor18
The Fetch-Execute cycle14
The processor instruction set10
Addressing modes8
Machine-Code Operations12
Shifts, Branching and Halting9
Interrupts10
Factors affecting processor performance9
Input and output devices11
Secondary storage devices15

Fundamentals of Communication and Networking15 subtopics

Serial and parallel transmission, networks and their topologies, wireless, the TCP/IP stack, application layer protocols, the client server model and thin-client computing. Examined on Paper 2.

Communication methods11
Communication basics14
Network Topology and Types of Networking17
Wireless networking14
The Internet and Packet Switching10
Routing, URLs and Domain Names14
Firewalls and How They Work10
Digital Signatures and Certificates14
TCP/IP15
Standard application layer protocols18
IP Address Structure and Subnet Masking12
IP Standards and Public and Private Addresses12
DHCP and Network Address Translation17
Client server model18
Thin- versus thick-client computing8

Consequences of Uses of Computing2 subtopics

The individual, social, legal and cultural issues that computing raises, and how to argue about them from concrete cases rather than generalities. Examined on Paper 2.

The Four Kinds of Issue in Computing11
Legislating for New Technology15

Systematic Approach to Problem Solving2 subtopics

The stages of software development, from analysis and design through implementation to testing and evaluation. Supplies the skills Paper 1 draws on and the standard the project is marked against.

Analysis and Establishing Requirements12
Testing and Selecting Test Data12

Fundamentals of Databases5 subtopics

Entity relationship modelling, relational databases and their keys, normalisation to third normal form, SQL, and managing concurrent access in a client server database. Examined on Paper 2.

Conceptual data models and entity relationship modelling13
Relational databases12
Database design and normalisation techniques15
Structured Query Language (SQL)17
Client server databases12

Big Data4 subtopics

What makes data 'big', why a lack of structure rather than size defeats a relational database, distributed processing and the functional style that suits it, and fact-based and graph representations. Examined on Paper 2.

Volume, Velocity and Variety11
Why Big Data Resists Analysis10
Distributed Processing and Functional Programming11
Fact-Based Models and Graph Schemas10

Fundamentals of Functional Programming4 subtopics

Function types, domain and co-domain, composition and partial application, higher-order functions, and lists built from a head and a tail. Examined on Paper 2.

Function Types, Domain and Co-Domain14
Partial Function Application14
Writing functional programs16
Lists in functional programming18

Sample questions

Taken from the AQA A-Level Computer Science guide. Answer each one closed book first, then open the answer.

Fundamentals of Programming

Why is a telephone number normally stored as a string rather than as an integer?

Show the answer
Because it is a sequence of digit symbols, not a quantity. It may begin with a leading zero that an integer would discard, it may contain spaces or a plus sign, it may be longer than the largest integer the language supports, and no arithmetic is ever performed on it.
Fundamentals of Data Structures

Why do programmers choose a particular data structure for a problem?

Show the answer
Because the structure determines how efficiently the operations the program needs most can be carried out. Choosing a structure whose natural operations match the problem gives faster code and simpler logic, for example a queue for jobs waiting for a printer, a stack for undo history, a graph for a road network, a hash table for fast lookup by key.
Fundamentals of Algorithms

What does it mean to traverse a graph?

Show the answer
To visit every vertex of the graph exactly once, following the edges, in a systematic order defined by the traversal algorithm. Because a graph may contain cycles, the traversal must record which vertices have already been visited so that it does not go round for ever.
Theory of Computation

What is sequence, and give a pseudo-code example?

Show the answer
Sequence means the steps are carried out one after another in the order written, each finishing before the next begins. For example: radius ← 5 area ← 1.5 * radius * radius OUTPUT area The order matters: if the OUTPUT line came first, area would not yet hold a value.
Fundamentals of Data Representation

What is a natural number, and what is the set ℕ?

Show the answer
A natural number is a whole, non-negative number used for counting. The set of natural numbers is ℕ = {0, 1, 2, 3, …}. It includes zero, it has no upper limit, and it contains no negative numbers and no fractions.
Fundamentals of Computer Systems

Why can a computer's function be changed without changing any of its physical parts?

Show the answer
Because the machine is general purpose: its behaviour is determined by the program stored in memory rather than by its wiring. Loading a different program changes what the same hardware does, so one machine can be a word processor, a games console and a web server on different occasions.
Fundamentals of Computer Organisation and Architecture

A machine has a 20-line address bus and each addressable location holds one byte. What is the maximum size of main memory it can address, and why?

Show the answer
Two to the power 20 locations, which is 1,048,576 bytes, or 1 mebibyte. The reason is that 20 binary lines can carry 2 to the power 20 different patterns, so that is the number of distinct addresses that can be placed on the bus. Fitting more physical memory than that would be pointless, because the processor would have no way to name the extra locations.
Fundamentals of Communication and Networking

Parallel transmission sends eight bits at once and serial only one. So why is a serial link often faster in practice?

Show the answer
Because the achievable clock rate matters more than the number of wires. A parallel link is limited by skew and crosstalk, so its clock must be kept low enough that all eight bits still arrive within the same window. A serial link has neither problem, so it can be clocked at a far higher frequency. A single wire running many times faster beats eight wires running slowly.

Questions about this guide

How do you use active recall for AQA A-Level Computer Science?

Answer up to 10 questions cold and closed book. Answer the same questions again open book, writing the correct answer down. Then answer them closed book one more time. The difference between the first and third attempt is what has moved into recall.

How is AQA A-Level Computer Science assessed?

AQA A-Level Computer Science is assessed by 3 components: Paper 1, on-screen exam (2 hours 30 minutes, 100 marks, 40%); Paper 2, written exam (2 hours 30 minutes, 100 marks, 40%); Non-exam assessment, the computing practical project (75 marks, 20%).

What topics does the AQA A-Level Computer Science active recall guide cover?

It covers Fundamentals of Programming, Fundamentals of Data Structures, Fundamentals of Algorithms, Theory of Computation, Fundamentals of Data Representation, Fundamentals of Computer Systems, Fundamentals of Computer Organisation and Architecture, Fundamentals of Communication and Networking, Consequences of Uses of Computing, Systematic Approach to Problem Solving, Fundamentals of Databases, Big Data and Fundamentals of Functional Programming.

Is the AQA A-Level Computer Science guide a PDF?

Yes. It is a digital PDF sent to the email address on your order after purchase. Check the address is correct at checkout, and check junk or spam if it has not arrived.

Does the guide include the answers?

Yes. Every question has its answer in the same document, grouped by topic, so step 2 of the method is done from the guide.