Edexcel GCSE Computer Science scheme of work

Lessons

1. The purpose of the CPU
2. CPU components
3. Von Neumann architecture
4. The fetch-decode-execute cycle
5. The clock and the buses
6. Embedded systems
7. Bringing it together

By the end, pupils can

• State the purpose of the CPU as fetching, decoding and executing instructions.
• Describe the functions of the ALU and the control unit.
• Describe the von Neumann stored program concept, with instructions and data held together in main memory.
• Identify what the program counter, MAR, MDR and accumulator hold during the fetch-decode-execute cycle.
• Describe each stage of the fetch-decode-execute cycle, naming the registers used at every step.

Lessons

1. Binary and unsigned integers
2. Two’s complement signed integers
3. Binary addition and overflow
4. Binary shifts
5. Hexadecimal
6. Characters and bitmap images
7. Sound and the limits of binary
8. Units of data and file sizes
9. Bringing it together

By the end, pupils can

• Explain why computers use binary and work out how many states a bit pattern can represent.
• Convert between denary and 8-bit binary, both unsigned (0 to 255) and two’s complement (−128 to +127).
• Add two positive binary patterns and explain when and why overflow occurs.
• Apply logical and arithmetic shifts and describe their effect on a value.
• Explain why hexadecimal is used and convert between hexadecimal and binary.

Lessons

1. Units of data storage
2. Calculating file sizes
3. The need for compression
4. Lossless and lossy compression
5. Encryption
6. Bringing it together

By the end, pupils can

• Define a bit, nibble and byte and order the binary multiples from kibibyte to tebibyte.
• Convert between units of data storage using multiples of 8 and 1024.
• Construct expressions to calculate image and sound file sizes and data capacity requirements.
• Explain the need for data compression, including its benefits and drawbacks.
• Compare lossless and lossy compression and choose the right method for a given file.

Lessons

1. Decomposition, abstraction and subprograms
2. Writing algorithms
3. Variables, constants and data structures
4. Operators
5. Trace tables and errors
6. Searching algorithms
7. Sorting algorithms
8. Evaluating algorithms
9. Bringing it together

By the end, pupils can

• Explain how decomposition and abstraction help model the real world and solve problems, and the benefits of subprograms.
• Follow and write algorithms as flowcharts, pseudocode and Python using sequence, selection, repetition and iteration.
• Use variables, constants, strings, one- and two-dimensional arrays and records in algorithms.
• Apply arithmetic, relational and logical operators, including modulus and integer division.
• Determine the output of an algorithm and complete trace tables to find variable values.

Lessons

1. Logic and Boolean values
2. AND, OR and NOT
3. Building truth tables
4. Three-input truth tables
5. Solving problems with logic
6. Logic in programs
7. Bringing it together

By the end, pupils can

• Explain what a Boolean value is and represent true and false as 1 and 0.
• Describe the effect of the AND, OR and NOT logical operators.
• Work out how many rows a truth table needs for one, two or three inputs.
• Complete truth tables with up to three inputs, using working columns and brackets.
• Write logic expressions from real-life descriptions of a system.

Lessons

1. Developing code
2. Data types, variables and operators
3. Programming constructs
4. Strings and data structures
5. Input, output and files
6. Validation and authentication
7. Subprograms
8. Errors, testing and evaluation
9. Bringing it together

By the end, pupils can

• Use decomposition and abstraction to plan a program, and write readable Python with comments, meaningful identifiers and indentation.
• Choose suitable data types, variables and constants, and use arithmetic, relational and logical operators.
• Write programs using sequence, selection with if, elif and else, and count-controlled and condition-controlled loops.
• Manipulate strings and use lists, two-dimensional lists and records.
• Accept user input, format output and read from and write to CSV text files.

Lessons

1. Why networks and types of network
2. How the internet is structured
3. Wired and wireless connectivity
4. Network speeds and calculations
5. Network protocols
6. The TCP/IP model
7. Network topologies
8. Bringing it together

By the end, pupils can

• Explain why computers are connected in a network and compare LANs and WANs.
• Describe how the internet is structured, including the role of routers and IP addresses.
• Explain how speed, range, latency and bandwidth differ for wired and wireless connections.
• Construct expressions linking file size, transmission rate and time, using bits per second.
• Describe the role of and need for Ethernet, Wi-Fi, TCP/IP, HTTP, HTTPS, FTP, POP3, SMTP and IMAP.

Lessons

1. Why network security matters
2. Identifying network vulnerabilities
3. Access control
4. Physical security
5. Firewalls
6. Bringing it together

By the end, pupils can

• Explain why network security is important, using the terms vulnerability and malicious hacker.
• Describe the consequences for an organisation if its network security is breached.
• Describe how penetration testing is used to identify network vulnerabilities.
• Explain what ethical hacking is and how it differs from malicious hacking.
• Describe how access control, including authentication and access rights, protects a network.

Lessons

1. The role of secondary storage
2. How data is stored on devices
3. Operating systems
4. Utility software
5. Robust software and vulnerabilities
6. Low-level and high-level languages
7. Compilers and interpreters
8. Bringing it together

By the end, pupils can

• Explain the role of secondary storage and why non-volatile storage is needed alongside RAM.
• Describe how magnetic, optical and solid-state devices store data, and compare their characteristics.
• Describe the purpose of an operating system and its file, process, peripheral and user management functions.
• Explain the purpose of file repair, backup, data compression, disk defragmentation and anti-malware utilities.
• Explain why robust software matters and how code reviews and audit trails identify vulnerabilities.

Lessons

1. Environmental issues
2. Personal data
3. AI, machine learning and robotics
4. Intellectual property
5. Malware
6. How hackers attack
7. Protecting digital systems and data
8. Bringing it together

By the end, pupils can

• Explain the environmental issues of manufacturing, using, replacing and disposing of digital devices.
• Explain the ethical and legal issues of collecting and using personal data, including privacy, consent and data protection.
• Discuss the accountability, safety, algorithmic bias and legal liability issues of AI, machine learning and robotics.
• Compare copyright, patents, trademarks and licences, including open-source and proprietary software.
• Describe how viruses, worms, Trojans, ransomware and key loggers threaten digital systems.