📚 Core Knowledge Review for Year 7 AQA Computer Science | 七年级 AQA 计算机：核心知识点梳理
Welcome to your essential guide to Year 7 AQA Computer Science. This article brings together the most important concepts you will encounter, from the basic building blocks of a computer system to the fundamentals of programming and staying safe online. Each section pairs an English explanation with a Chinese one so that you can build both your subject knowledge and your technical vocabulary at the same time.
欢迎阅读七年级 AQA 计算机科学的核心知识指南。这篇文章汇集了你会遇到的最重要的概念，从计算机系统的基本组成部分到编程基础和网络安全。每一部分都提供了英文解释和对应的中文解释，帮助你同时建立学科知识和专业词汇。
1. What Is a Computer System? | 什么是计算机系统？
A computer system is a combination of hardware and software that works together to process data. Hardware refers to the physical parts you can touch, like the keyboard, monitor, and the internal components inside the case. Software is the collection of instructions that tells the hardware what to do.
计算机系统是硬件和软件相互配合来处理数据的组合。硬件指的是你可以触摸到的物理部件，比如键盘、显示器以及机箱内部的组件。软件则是告诉硬件该做什么的指令集合。
utput model. You give the computer data through an input device, the central processing unit (CPU) carries out instructions on that data, and then the results are shown through an output device. A smartphone, a laptop, a games console, and even a microwave with digital controls are all examples of computer systems.
核心思想是输入 → 处理 → 输出模型。你通过输入设备将数据交给计算机，中央处理器 (CPU) 对这些数据执行指令，然后结果通过输出设备显示出来。智能手机、笔记本电脑、游戏机，甚至带有数字控制的微波炉都是计算机系统的例子。
2. Hardware: Input, Output, and Storage Devices | 硬件：输入、输出和存储设备
Hardware can be grouped into three main types. Input devices let you send data into the computer; examples include a mouse, keyboard, touchscreen, microphone, and webcam. Output devices show or play the results; examples include a monitor, printer, speakers, and headphones.
硬件可以分为三大类。输入设备让你把数据送入计算机；例如鼠标、键盘、触摸屏、麦克风和摄像头。输出设备用于显示或播放结果；例如显示器、打印机、扬声器和耳机。
Storage devices keep data and programs safe when the power is turned off. Primary storage, called RAM, temporarily holds the data and instructions the CPU is working on right now. Secondary storage is for long-term saving and includes the hard disk drive (HDD), solid-state drive (SSD), USB flash drives, and cloud storage accessed over the internet.
存储设备在断电时保存数据和程序。主存储器称为 RAM，暂时存放 CPU 正在处理的数据和指令。辅助存储器用于长期保存，包括机械硬盘 (HDD)、固态硬盘 (SSD)、USB 闪存驱动器以及通过互联网访问的云存储。
3. Software: Systems and Applications | 软件：系统软件和应用软件
Software is divided into two broad categories. System software runs the computer itself and manages its resources. The most important piece of system software is the operating system (OS), like Windows, macOS, iOS, or Android. The OS manages files, controls hardware devices, provides a user interface, and allows you to run other programs.
软件可以分为两大类。系统软件负责运行计算机本身并管理其资源。最重要的系统软件是操作系统 (OS)，比如 Windows、macOS、iOS 或 Android。操作系统管理文件、控制硬件设备、提供用户界面并允许你运行其他程序。
Application software is designed to help the user perform specific tasks. Word processors, spreadsheets, web browsers, games, and photo editors are all examples. Utility software is a special type of system software that helps maintain and protect the computer, such as antivirus programs, backup tools, and disk cleaners.
应用软件旨在帮助用户完成特定任务。文字处理软件、电子表格、网页浏览器、游戏和照片编辑器都是例子。实用工具软件是一类特殊的系统软件，帮助维护和保护计算机，例如防病毒程序、备份工具和磁盘清理工具。
4. Why Computers Use Binary | 为什么计算机使用二进制
Computers do not understand words, pictures, or sounds directly. Everything inside a computer is represented using only two symbols: 0 and 1. This number system is called binary, or base-2. The reason is that the tiny electronic switches inside a computer, called transistors, can be either off (0) or on (1) very reliably.
计算机并不直接理解文字、图片或声音。计算机内部的一切都只用两个符号表示：0 和 1。这种数制称为二进制，即基数为 2。原因是计算机内部的微小电子开关（称为晶体管）能够非常可靠地处于断开 (0) 或闭合 (1) 状态。
A single binary digit (0 or 1) is called a bit. Eight bits make up one byte. Using groups of bits, we can represent larger numbers, letters of the alphabet, colours in an image, and much more. Understanding binary will help you grasp how data of all kinds is stored and processed digitally.
单个二进制数字（0 或 1）称为一个比特。八个比特组成一个字节。利用比特的组合，我们可以表示更大的数字、字母表中的字母、图像中的颜色，等等。理解二进制将帮助你掌握各种数据是如何被数字化地存储和处理的。
5. How Data Is Represented: Text, Images, and Sound | 数据如何表示：文本、图像和声音
Every type of data follows a coding system so that the computer can store it in binary. Text is commonly represented using the ASCII code, where each character is assigned a unique 7-bit binary number. For example, the uppercase letter 'A' is 100 0001 in binary. Modern systems often use Unicode, which can represent characters from nearly all the world's writing systems.
每种数据类型都遵循一套编码系统，使计算机能够以二进制形式存储它。文本通常使用 ASCII 码表示，其中每个字符被分配一个唯一的 7 位二进制数。例如，大写字母 'A' 对应的二进制是 100 0001。现代系统常使用 Unicode，它几乎能表示世界上所有的文字系统。
Images are made up of tiny dots called pixels. Each pixel is given a binary code that describes its colour. In a black-and-white image, one bit per pixel might be enough (0 for white, 1 for black), but for full-colour images many more bits are needed per pixel. Sound is represented by taking thousands of samples of the sound wave every second and converting each measurement into a binary value. The more bits used per sample, the better the sound quality.
图像由称为像素的小点组成。每个像素获得一个描述其颜色的二进制代码。在黑白图像中，每个像素可能只需要一个比特（0 代表白，1 代表黑），但对于全彩图像，每个像素需要多得多的比特。声音的表示方法是每秒对声波进行数千次采样，并将每次测量值转换为二进制值。每次采样使用的比特越多，音质越好。
6. Introduction to Algorithms | 算法入门
An algorithm is a step-by-step set of instructions designed to solve a problem or complete a task. You follow algorithms in everyday life: a recipe for baking a cake, the instructions for building a Lego model, or the steps for getting ready for school in the morning are all algorithms. In computer science, algorithms must be precise, unambiguous, and they must have a clear start and end.
算法是一套分步骤的指令，旨在解决问题或完成任务。你在日常生活中经常遵循算法：烤蛋糕的食谱、搭乐高模型的说明书，或者早上准备上学的步骤都是算法。在计算机科学中，算法必须精确、无歧义，并且必须有清晰的起点和终点。
When designing an algorithm, we think about the inputs needed, the process to follow, and the expected outputs. Good algorithms are efficient and solve the problem with the fewest possible steps or resources. Algorithms can be expressed in plain English, as a flowchart, or using pseudocode, which is a simplified programming-like language.
在设计算法时，我们要考虑所需的输入、要遵循的处理过程以及预期的输出。好的算法是高效的，能以尽可能少的步骤或资源解决问题。算法可以用简单的英语、流程图或伪代码（一种简化的类编程语言）来表达。
7. Programming Basics: Sequence, Selection, and Iteration | 编程基础：顺序、选择和循环
All computer programs are built from three fundamental control structures. Sequence means executing instructions one after another, in the exact order they are written. This is the simplest structure: do step 1, then step 2, then step 3.
所有计算机程序都由三种基本控制结构构建而成。顺序意味着按照指令编写的精确顺序一条接一条地执行。这是最简单的结构：做步骤 1，然后步骤 2，然后步骤 3。
Selection allows the program to make decisions. It uses conditions that evaluate to either true or false, and then the program follows different paths depending on the result. In most programming languages, this is done using IF, ELSE IF, and ELSE statements. For example, IF the password is correct THEN allow login ELSE show an error message.
选择让程序能够做出决策。它使用计算结果为真或假的条件，然后程序根据结果走不同的执行路径。在大多数编程语言中，这是通过 IF、ELSE IF 和 ELSE 语句来完成的。例如，IF 密码正确 THEN 允许登录 ELSE 显示错误信息。
Iteration means repeating a block of code. There are two main types: count-controlled loops (like FOR loops), which repeat a set number of times, and condition-controlled loops (like WHILE loops), which repeat as long as a condition remains true. Iteration is what makes computers powerful, allowing them to perform repetitive tasks quickly and accurately.
循环意味着重复执行一段代码。主要有两种类型：计数控制循环（如 FOR 循环），它重复固定次数；以及条件控制循环（如 WHILE 循环），只要条件保持为真就继续重复。循环正是计算机强大的原因，让它们能够快速而准确地执行重复性任务。
8. Computational Thinking and Decomposition | 计算思维与分解
Computational thinking is a set of skills for solving problems in a way that a computer could help. It includes four key techniques. Decomposition means breaking a large, complex problem down into smaller, more manageable parts. For example, designing a school website can be broken down into planning the layout, writing text, sourcing images, and coding each page.
计算思维是一套以计算机能够提供帮助的方式来解决问题的技能。它包括四种关键技术。分解意味着将一个庞大复杂的问题拆解成更小、更易管理的部分。例如，设计一个学校网站可以分解为规划布局、撰写文字、寻找图片以及编写每个页面的代码。
Pattern recognition involves spotting similarities or trends within or between problems. If you recognise that the same kind of loop is needed in several places, you can reuse the idea. Abstraction is about focusing on the important information only and ignoring irrelevant detail. When drawing a map of a bus route, you only need stations and roads, not every tree. Finally, algorithm design is the process of creating the step-by-step solution.
模式识别涉及在问题内部或问题之间发现相似性或趋势。如果你识别出在几个地方需要同一种循环，你就可以重复使用这个思路。抽象是指只关注重要信息，忽略不相关的细节。在画公交路线图时，你只需要站点和道路，而不需要每棵树。最后，算法设计是创建分步骤解决方案的过程。
9. Computer Networks and the Internet | 计算机网络与互联网
A computer network is two or more computers connected together so they can share data and resources. A Local Area Network (LAN) covers a small geographical area, such as a school or an office building. A Wide Area Network (WAN) connects computers over a larger area, like across cities or countries. The internet is the largest WAN, a global network of networks.
计算机网络是两台或多台计算机连接在一起，以便它们可以共享数据和资源。局域网 (LAN) 覆盖一个较小的地理区域，例如一所学校或一栋办公楼。广域网 (WAN) 连接更大范围内的计算机，例如跨越城市或国家。互联网就是最大的广域网，是一个全球性的网络之网络。
Networks can be wired, using Ethernet cables, or wireless, using Wi‑Fi. Key hardware includes routers, which direct data between networks, and switches, which connect devices within the same network. The World Wide Web is a service that runs on the internet, consisting of web pages accessed through a browser using protocols like HTTP and HTTPS. The internet also supports email, video calls, online gaming, and file transfers.
网络可以是有线的，使用以太网线缆，也可以是无线的，使用 Wi‑Fi。关键的网络硬件包括路由器（在网间引导数据）和交换机（在同一网络内连接设备）。万维网是运行在互联网之上的一项服务，由网页组成，通过浏览器使用 HTTP 和 HTTPS 等协议访问。互联网还支持电子邮件、视频通话、在线游戏和文件传输。
10. Staying Safe and Responsible Online | 网络安全与负责任的上网行为
Staying safe online is a vital part of being a digital citizen. You should always keep personal information private: do not share your full name, address, phone number, school name, or passwords with strangers or on public websites. Create strong passwords using a mix of letters, numbers, and symbols, and never share them with friends.
安全上网是成为数字公民的重要一环。你应当始终保护个人信息的私密性：不要向陌生人或在公开网站上分享你的全名、地址、电话号码、学校名称或密码。使用字母、数字和符号的组合来创建强密码，并且绝不与朋友分享。
Cyberbullying is bullying that takes place through electronic devices. If you experience or witness it, tell a trusted adult. Be respectful in all online communication. Also, be critical of information you find online; not everything you read is true. Check sources and look for other evidence before believing or sharing something.
网络欺凌是通过电子设备发生的欺凌行为。如果你经历或目睹了它，请告诉你信任的成年人。在所有在线交流中都要保持尊重。同时，对你在网上找到的信息要保持批判性；不是所有你读到的东西都是真实的。在相信或分享某些内容之前，要检查来源并寻找其他证据。
Copyright law applies online too. You must not download or share music, films, or images without permission. Always credit the creator when using someone else's work. Finally, be aware of malware like viruses and phishing scams. Do not open suspicious emails or click unknown links, and always keep your software up to date.
版权法同样适用于网络。未经许可，你不能下载或分享音乐、电影或图片。在使用他人的作品时，务必署名致谢。最后，要警惕病毒等恶意软件和网络钓鱼诈骗。不要打开可疑的电子邮件或点击未知链接，并始终保持你的软件更新。
11. Key Programming Vocabulary | 核心编程词汇
Building a strong vocabulary helps you read, write, and debug code confidently. A variable is a named container that holds a value which can change as the program runs, like a score in a game. A constant is similar but its value stays the same throughout the program. A function (or procedure) is a named block of code that performs a specific task and can be reused whenever needed.
建立扎实的词汇基础有助于你自信地阅读、编写和调试代码。变量是一个命名的容器，存放着在程序运行时可改变的值，比如游戏中的得分。常量与之类似，但其值在整个程序中保持不变。函数（或过程）是一个命名的代码块，用于执行特定任务，可以在需要时重复使用。
Syntax refers to the strict set of rules that define how code must be written in a given language, just like grammar in English. A logic error is a mistake in the way the program thinks, so it runs without crashing but produces wrong results. Debugging is the process of finding and fixing these errors. You will also come across terms like string (a sequence of characters), integer (a whole number), and Boolean (a true or false value).
语法指的是一套严格的规则，规定了代码在给定语言中必须如何书写，就像英语中的语法一样。逻辑错误是程序思考方式上的错误，因此它运行时不会崩溃，但会产生错误的结果。调试是寻找并修复这些错误的过程。你还会遇到诸如字符串（一串字符）、整数（一个整数）和布尔值（一个真或假的值）等术语。
12. Putting It All Together: From Problem to Program | 综合运用：从问题到程序
When faced with a computing problem, always start by reading the task carefully and identifying exactly what inputs are available and what outputs are expected. Next, use decomposition to break the problem into smaller chunks. Look for patterns and decide what abstractions you can make to simplify the work.
面对一个计算问题时，始终要从仔细阅读任务开始，准确识别可用的输入和期望的输出。接下来，使用分解将问题拆解成更小的块。寻找模式，并决定可以通过哪些抽象来简化工作。
Design your algorithm using a flowchart or pseudocode on paper before you start typing any code. This helps you think through the logic without getting distracted by syntax. Check your design by tracing through the steps with sample data. Once you are happy with the plan, write the code in your chosen programming language, paying attention to sequence, selection, and iteration. Finally, test your program thoroughly with a range of inputs, including edge cases, to make sure it works correctly under all conditions.
在开始键入任何代码之前，先在纸上用流程图或伪代码设计你的算法。这有助于你在不被语法干扰的情况下把逻辑思考清楚。通过用样本数据逐步追踪来检查你的设计。一旦你对计划满意了，就可以用你选择的编程语言编写代码，注意顺序、选择和循环。最后，用各种输入（包括边界情况）彻底测试你的程序，确保它在所有条件下都能正确工作。
Revising these core ideas regularly will build your confidence and give you a solid foundation for the rest of your Computer Science journey at AQA. Keep asking questions, practice writing algorithms for fun, and explore the technology around you with curiosity.
定期复习这些核心思想将建立你的信心，并为你后续的 AQA 计算机科学之旅打下坚实基础。保持提问，为了乐趣而练习编写算法，并带着好奇心探索身边的技术。
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