A-Level Computer Science Paper 2

Overview of A-Level Paper 2 Computer Science

• The lecture is an introduction to A-Level Paper 2 for Computer Science (syllabus code 961).
• The exam duration is 2 hours, with a total of 75 marks.
• The paper is a written exam, similar to the O-Level Paper 2 format.
• While the exam focuses on pseudocode, students will also be taught Python for skill development and knowledge.
• A "Diamond Book" workbook has been created to aid in solving the paper, including lectures, solutions, and past paper practice.
• There are four chapters in the syllabus: Chapter 9, Chapter 10, Chapter 11, and Chapter 12. The goal is to cover Chapter 9 in the current class.
• A set of 13 books, including the Diamond Book, a planner, a revision book, and past papers for both Paper 1 and Paper 2, are available.

Introduction to Computational Thinking Skills

• Computational thinking is defined as the process of studying a problem and formulating an effective solution using computers.
• Involves using computer to study and solve problems
• Techniques include abstraction, decomposition, algorithms, and pattern recognition.
• Focus in algorithms includes structured English, flowcharts, and pseudocode.

Abstraction

• Abstraction involves extracting essential information while ignoring irrelevant details.
• The focus is on keeping key elements and discarding unnecessary information.
• Example: Filtering out irrelevant information from a client's description of their business to focus on the technical requirements.

Decomposition

• Decomposition involves breaking down a complex problem into smaller, manageable parts (modules).
• Modules make it easier to manage code.
• Allows for easier teamwork, as different teams can work on different modules.
• Reduces the impact of errors, as a problem in one module does not affect the entire program.
• An example includes Instagram and their story updates, each update is a "module" of code that then updates access to all the users.

Pattern Recognition

• Pattern recognition recognizes similar techniques or code blocks across different modules.
• Involves identifying similarities between modules and creating a reusable module for those common elements.
• Example: Identifying that two modules both use the same addition technique and creating a separate module for addition that both can call.
• Steps include identifying similar parts of a problem and creating reusable programming code, which is stored in a module (subroutine, function, or procedure).

Algorithms

• Algorithms involve writing tasks step by step in an ordered sequence.
• Algorithms can be written in multiple ways:
  • Step by step
  • Structured English
  • Flow chart
  • SuDoCo code
• The book for learning Python coding is called The Purple Book

Pseudocode

• When you switch on a computer, you need a high-level language in order to access the CPU
• Cambridge suggests three High-Level languages:
  • Python
  • Java
  • Visual Basic
• A2 has a practical paper named Paper Four
• Paper four is on a high level language
• You need to write Python source code onto a computer
• A general programming skill known as "SuDoCo code" is used on the written paper

Standard Methods of Solution and Programming Techniques

• Several standard methods and techniques are commonly used in pseudocode:
  • Totalling: Accumulating a sum (e.g., Total = Total + Number).
  • Counting: Incrementing a counter (e.g., Count = Count + 1).
  • Finding the Largest/Smallest Number: Iterating through a list to find the largest or smallest value.
  • Linear Search: Searching each element in an array one by one.
  • Binary Search: A search algorithm that involves splitting data into testing for larger or smaller
  • Sorting: Arranging data in a specific order, with Bubble Sort being mentioned.
• These techniques serve as standard solutions within programming.

Structured English

• Structured English involves writing programming logic in plain English for better understanding.
• It's a method of showing logical steps in clear, straightforward English.
• Can include numbering and keywords
• Example:
  • Set total to zero
  • Enter value for all numbers
  • If N<output