📚 Year 8 WJEC Computer Science: Core Knowledge Overview | Year 8 WJEC 计算机：核心知识点梳理
This guide provides a structured overview of the core topics in the Year 8 WJEC Computer Science curriculum. It is designed to help students review key concepts, from understanding hardware and binary to programming logic and online safety, in a clear and bilingual format.
本指南系统地梳理了 Year 8 WJEC 计算机科学课程的核心主题。它旨在帮助学生以清晰的双语形式复习关键概念，从理解硬件和二进制到编程逻辑和网络安全。
1. Computer Systems and Hardware | 计算机系统与硬件
A computer system consists of hardware (physical components) and software (programs) that work together. The Central Processing Unit (CPU) is often called the 'brain' of the computer because it executes instructions.
计算机系统由相互协作的硬件（物理部件）和软件（程序）组成。中央处理器（CPU）常被称为计算机的“大脑”，因为它负责执行指令。
Main hardware components include the CPU, main memory (RAM and ROM), and secondary storage. RAM is volatile memory used to temporarily hold data and programs currently in use, while ROM contains permanent startup instructions.
主要硬件组件包括 CPU、主存储器（RAM 和 ROM）以及辅助存储器。RAM 是易失性存储器，用于临时存放正在使用的数据和程序，而 ROM 包含永久性的启动指令。
Input devices (e.g. keyboard, mouse, microphone) send data into the computer. Output devices (e.g. monitor, speakers, printer) display or present information to the user.
输入设备（如键盘、鼠标、麦克风）将数据送入计算机。输出设备（如显示器、扬声器、打印机）向用户展示或呈现信息。
Secondary storage devices, such as Hard Disk Drives (HDD) and Solid-State Drives (SSD), provide long-term, non-volatile storage for files and software.
辅助存储设备，如硬盘驱动器（HDD）和固态驱动器（SSD），为文件和软件提供长期、非易失性的存储。
2. Software: System and Application | 软件：系统软件与应用软件
Software is divided into two main categories: system software and application software. System software manages the hardware and provides a platform for other programs to run.
软件分为两大类：系统软件和应用软件。系统软件管理硬件并为其他程序的运行提供平台。
The Operating System (OS) is the most important system software. It handles tasks such as managing memory, controlling input/output devices, providing a user interface, and allowing multiple applications to run at once.
操作系统（OS）是最重要的系统软件。它负责处理内存管理、控制输入输出设备、提供用户界面以及允许多个应用程序同时运行等任务。
Utility programs are a type of system software that perform maintenance tasks, e.g. antivirus scanners, disk defragmenters, and backup tools.
实用程序是一类执行维护任务的系统软件，例如防病毒扫描程序、磁盘碎片整理程序和备份工具。
Application software is designed to help users perform specific tasks. Common examples include word processors (to create documents), spreadsheets (to manage data), web browsers, and presentation software.
应用软件旨在帮助用户执行特定任务。常见的例子包括文字处理软件（用于创建文档）、电子表格（用于管理数据）、网页浏览器和演示软件。
3. Data Representation: Binary and Bits | 数据表示：二进制与位
Computers use binary, a base‑2 number system, because their circuits have two states: on (1) and off (0). A single binary digit is called a bit, and 8 bits make up 1 byte.
计算机使用二进制（以 2 为基的数制），因为其电路只有两种状态：开（1）和关（0）。一个单独的二进制数字称为一位（bit），8 位构成一个字节（byte）。
converted to decimal by adding the place values where a 1 appears. For example, 1010₂ = 1 × 2³ + 0 × 2² + 1 × 2¹ + 0 × 2⁰ = 8 + 0 + 2 + 0 = 10 in decimal.
二进制数可通过加和出现 1 的位权值转换为十进制。例如，1010₂ = 1 × 2³ + 0 × 2² + 1 × 2¹ + 0 × 2⁰ = 8 + 0 + 2 + 0 = 10（十进制）。
Characters are represented using codes such as ASCII, where each letter, digit, or symbol is assigned a unique binary number. 'A' is 65 (01000001 in binary).
字符使用诸如 ASCII 等编码表示，每个字母、数字或符号都分配了一个唯一的二进制数。例如 'A' 是 65（二进制 01000001）。
Images and sound are also stored as binary data. A bitmap image is broken into pixels, each assigned a binary value for its colour. Sound is sampled at regular intervals and each sample is converted to a binary number.
图像和声音也以二进制数据形式存储。位图图像被分解为像素，每个像素分配一个代表其颜色的二进制值。声音按固定间隔采样，每个采样点被转换为一个二进制数。
4. Logic Gates and Truth Tables | 逻辑门与真值表
Logic gates are the building blocks of digital circuits. They take one or more binary inputs and produce a single binary output based on a logical rule.
逻辑门是数字电路的构建模块。它们接收一个或多个二进制输入，并根据逻辑规则产生一个二进制输出。
The AND gate gives output 1 only when all inputs are 1. The OR gate gives output 1 when at least one input is 1. The NOT gate inverts the input (0 becomes 1, 1 becomes 0).
与门（AND）仅在所有输入均为 1 时输出 1。或门（OR）在至少一个输入为 1 时输出 1。非门（NOT）将输入反转（0 变 1，1 变 0）。
Truth table for the AND gate:
| A | B | Output |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
与门真值表：
| A | B | 输出 |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
5. Algorithms and Flowcharts | 算法与流程图
An algorithm is a step-by-step set of instructions to solve a problem or complete a task. It must be clear, precise, and have a defined beginning and end.
算法是解决某个问题或完成某个任务的一组逐步操作的指令。它必须清晰、精确，并有明确的开始和结束。
Flowcharts are a visual way to represent algorithms using standard symbols: ovals for start/end, rectangles for processes, diamonds for decisions, and parallelograms for input/output.
流程图是一种用标准符号来直观表示算法的方法：椭圆表示开始/结束，矩形表示处理步骤，菱形表示判断，平行四边形表示输入/输出。
be shown as: Start → Input number1, number2 → sum = number1 + number2 → Output sum → End.
例如，计算两数之和的算法可以表示为：开始 → 输入 number1, number2 → sum = number1 + number2 → 输出 sum → 结束。
Algorithms should be tested with sample data to ensure they produce correct results. Tracing through a flowchart step by step helps identify logical errors.
算法应该用示例数据进行测试以确保产生正确的结果。逐步跟踪流程图有助于发现逻辑错误。
6. Introduction to Programming | 编程入门
Programming is the process of writing instructions for a computer to execute. Common languages for Year 8 include Scratch (block‑based) and Python (text‑based).
编程是为计算机编写要执行的指令的过程。Year 8 常用的语言包括 Scratch（基于积木块）和 Python（基于文本）。
Variables are used to store data during a program's execution. For example, in Python: score = 0. The value can be updated later in the code.
变量用于在程序执行期间存储数据。例如在 Python 中：score = 0。该值可以在代码中稍后更新。
Programs are built using three basic control structures: sequence (executing instructions in order), selection (making decisions using if‑statements), and iteration (repeating code with loops).
程序使用三种基本的控制结构来构建：顺序（按顺序执行指令）、选择（使用 if 语句进行决策）和迭代（使用循环重复代码）。
Example of selection: if age >= 13: print('Access granted') else: print('Access denied'). A while loop keeps repeating as long as a condition is true.
选择示例：if age >= 13: print('Access granted') else: print('Access denied')。while 循环只要条件为真就会一直重复执行。
7. Networks and the Internet | 网络与互联网
A network is two or more computers connected together to share resources and data. A Local Area Network (LAN) covers a small geographical area (e.g. a school), while a Wide Area Network (WAN) spans large distances.
网络是两台或更多计算机连接在一起以共享资源和数据。局域网（LAN）覆盖较小的地理区域（如学校），而广域网（WAN）跨越长距离。
The Internet is a global network of networks. It uses protocols such as TCP/IP to ensure reliable communication. The World Wide Web is a service on the Internet that allows access to webpages via browsers.
互联网是一个全球性的网络之网络。它使用 TCP/IP 等协议来确保可靠通信。万维网是互联网上的一项服务，允许通过浏览器访问网页。
Key network hardware includes routers, which direct data packets, and switches, which connect devices within a LAN. Each device on a network has a unique IP address.
关键的网络硬件包括路由器（负责导引数据包）和交换机（用于连接局域网内的设备）。网络上的每个设备都有一个唯一的 IP 地址。
A Domain Name System (DNS) server translates human‑friendly domain names (e.g. www.example.com) into IP addresses, making it easier to browse the web.
域名系统（DNS）服务器将人类友好的域名（如 www.example.com）转换为 IP 地址，使浏览网页更加容易。
8. Cybersecurity and Safe Practice | 网络安全与安全实践
Cybersecurity is the protection of computer systems, networks, and data from digital attacks. Common threats include viruses, phishing emails, and unauthorised access.
网络安全是对计算机系统、网络和数据免受数字攻击的保护。常见的威胁包括病毒、网络钓鱼电子邮件和未经授权的访问。
Using strong passwords (a mix of letters, numbers, and symbols) and not sharing them with others is a first line of defence. Two‑factor authentication adds an extra layer of security.
使用强密码（字母、数字和符号的组合）和不与他人共享密码是第一道防线。双因素验证增加了额外的安全层。
Personal information such as full name, address, and school should not be shared online without caution. Always check privacy settings on social media and gaming platforms.
个人信息，如全名、地址和学校，不应随意在网上分享。务必检查社交媒体和游戏平台上的隐私设置。
Organisations use firewalls to monitor incoming and outgoing traffic, and encryption to scramble data so that only authorised parties can read it. Being able to spot suspicious links and attachments helps prevent malware infection.
组织使用防火墙来监视传入和传出的流量，并使用加密技术对数据进行乱码处理，只有授权方才能读取。能够识别可疑的链接和附件有助于防止恶意软件感染。
9. Computational Thinking | 计算思维
Computational thinking is a problem‑solving approach that combines logical thinking with concepts from computer science. It consists of four main skills: decomposition, pattern recognition, abstraction, and algorithm design.
计算思维是一种结合了逻辑思维和计算机科学概念的解决问题的方法。它包括四项主要技能：分解、模式识别、抽象和算法设计。
Decomposition means breaking a large problem into smaller, more manageable parts. For example, organising a school trip can be divided into transport, food, and activities.
分解是指将一个大的问题分解成更小、更易于管理的部分。例如，组织一次学校旅行可以分解为交通、饮食和活动安排。
Pattern recognition involves identifying similarities or trends within problems. If a sorting task has been solved before, the same pattern can be reused.
模式识别涉及识别问题中的相似性或趋势。如果某个排序任务之前已经解决过，那么相同的模式可以被复用。
Abstraction focuses on the important details while ignoring irrelevant information. A map of a town ignores details like tree positions to highlight roads and landmarks.
抽象侧重于重要细节，同时忽略无关信息。一幅城镇地图会忽略诸如树木位置等细节，以突出道路和地标。
Algorithm design is the process of creating a step‑by‑step plan to solve the problem. These skills are used not only in programming but in many everyday situations.
算法设计是创建一个逐步计划来解决问题的过程。这些技能不仅用于编程，也用于许多日常情境。
10. Data Handling and Databases | 数据处理与数据库
A database is a structured collection of data stored electronically. It allows users to store, search, sort, and retrieve information efficiently.
数据库是以电子方式存储的结构化数据集合。它允许用户高效地存储、搜索、排序和检索信息。
Data in a database is organised into tables consisting of records (rows) and fields (columns). Each field has a specific data type, such as text, number, or date.
数据库中的数据被组织成由记录（行）和字段（列）组成的表。每个字段都有特定的数据类型，如文本、数字或日期。
Every table should have a primary key, a unique identifier for each record (e.g. StudentID), which prevents duplicate
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