📚 Year 11 CAIE Computer Science: Case Study Practical Exercises | 11年级CAIE计算机：案例分析实战演练
Case study questions in CAIE IGCSE Computer Science (0478/0984) assess your ability to apply theoretical knowledge to real-world scenarios. This article provides a structured approach to tackling these questions, covering decomposition, algorithm design, databases, logic circuits, cybersecurity, data representation, and system analysis. You will also find a complete practice case study with worked solutions.
CAIE IGCSE 计算机科学（0478/0984）中的案例分析题考查你将理论知识应用于真实场景的能力。本文提供了一套应对这些题目的结构化方法，涵盖问题分解、算法设计、数据库、逻辑电路、网络安全、数据表示和系统分析。你还会找到一个完整的实战案例，附有详细解答。
1. Understanding Case Studies in CAIE Exams | 理解CAIE考试中的案例分析
Case study questions present a scenario — a school library, a hospital record system or an online shop — followed by a series of sub-questions. You must read carefully, identify the key computing concepts being tested, and structure your responses logically. Marks are awarded for applying knowledge to the given context, not just recalling definitions.
案例分析题会给出一个场景，如学校图书馆、医院记录系统或网店，然后提出若干子问题。你必须仔细阅读，识别所考查的关键计算概念，并有逻辑地组织回答。得分的关键在于将知识应用于给定情境，而非仅仅背诵定义。
Typical question styles include explaining why a particular storage medium is suitable, writing pseudocode for a process described in the scenario, designing a database query to extract information, or evaluating the ethical impact of a system. Always link your answer to details provided in the case.
典型题型包括：解释某种存储介质为何适合，为场景中描述的过程编写伪代码，设计数据库查询提取信息，或评估系统的伦理影响。始终将你的答案与案例中提供的细节联系起来。
In Paper 1, case studies often appear in sections on hardware, software, data transmission and security. In Paper 2, they are embedded in algorithm design, programming logic and database tasks. Practising past papers with this mindset is the best preparation.
在Paper 1中，案例分析通常出现在硬件、软件、数据传输和安全部分。在Paper 2中，它们嵌入在算法设计、编程逻辑和数据库任务中。以这种思维练习历年试题是最佳准备方式。
2. Decomposition and Abstraction | 问题分解与抽象
When faced with a complex case study, break it down into smaller, manageable parts. Decomposition means identifying the main functions of the system and the data that flows between them. For example, a doctor’s surgery booking system can be decomposed into patient registration, appointment scheduling, prescription management and billing.
面对复杂的案例分析时，将其分解为更小、可管理的部分。问题分解意味着识别系统的主要功能以及它们之间流动的数据。例如，医生诊所预约系统可分解为病人注册、预约排班、处方管理和账单处理。
Abstraction is about focusing on the essential details while ignoring irrelevant ones. When modelling a traffic light system, you abstract away the colour shades and only care about red, amber, green and the timer. In your exam answer, show that you can abstract the key processes from the scenario description.
抽象是指关注重要细节，忽略无关信息。为交通灯系统建模时，你抽象掉颜色深浅，只关心红、黄、绿以及计时器。在考试答案中，要展示你能从场景描述中抽象出关键过程。
Use a structure chart or a simple numbered list to illustrate decomposition in your answers. This demonstrates computational thinking and often earns extra marks.
使用结构图或简单的编号列表在答案中说明问题分解，这展示了计算思维，经常能获得额外分数。
3. Algorithm Design with Flowcharts | 使用流程图设计算法
Many case studies ask you to suggest an algorithm for a specific task, such as calculating late return fines in a library system. You can represent your solution as a flowchart using standard symbols: oval for start/end, parallelogram for input/output, rectangle for processes, diamond for decisions and arrows for flow direction.
许多案例分析要求你为特定任务建议一种算法，例如计算图书馆系统逾期还书的罚款。你可以用标准流程图符号表示解决方案：椭圆表示开始/结束，平行四边形表示输入/输出，矩形表示处理过程，菱形表示判断，箭头表示流程方向。
Always initialise variables before using them. For example, set `fine = 0` at the start. Ensure your decision diamonds have clear ‘Yes’ and ‘No’ branches, and that your algorithm terminates. In CAIE exams, you may be asked to draw the flowchart or to identify errors in a given one.
使用变量前一定要初始化。例如，开始时设定 `fine = 0`。确保判断菱形有明确的“是”和“否”分支，并且算法能够终止。在CAIE考试中，可能会要求你画流程图，或找出给定流程图中的错误。
A well-structured flowchart for a library fine calculation might input `days_late`, then use a decision: if `days_late` > 7, fine = (days_late – 7) × 0.50 + 7 × 0.20; otherwise fine = days_late × 0.20. Output the fine. State any assumptions, such as the daily charge.
一个结构良好的图书馆罚款计算流程图可能是：输入 `days_late`，然后判断：如果 `days_late` > 7，fine = (days_late – 7) × 0.50 + 7 × 0.20；否则 fine = days_late × 0.20。输出罚款金额。说明任何假设，例如每日计费标准。
4. Pseudocode Walkthroughs | 伪代码演练
CAIE uses its own pseudocode style, which you must learn. It includes constructs like `INPUT`, `OUTPUT`, `IF … THEN … ELSE … ENDIF`, `FOR … TO … NEXT`, `WHILE … DO … ENDWHILE`, `REPEAT … UNTIL`, and `CASE OF … ENDCASE`. Use indentation to show structure clearly.
CAIE采用自己的伪代码风格，你必须学习。它包括 `INPUT`、`OUTPUT`、`IF … THEN … ELSE … ENDIF`、`FOR … TO … NEXT`、`WHILE … DO … ENDWHILE`、`REPEAT … UNTIL` 和 `CASE OF … ENDCASE` 等结构。用缩进清晰展示结构。
When writing pseudocode for a case study, declare variables at the top. Use meaningful names that relate to the context, such as `StudentName`, `BookID`, `ReturnDate`. Comment your code with `//` to explain key steps, which shows deeper understanding.
为案例分析编写伪代码时，在顶部声明变量。使用与上下文相关的有意义名称，如 `StudentName`、`BookID`、`ReturnDate`。用 `//` 注释关键步骤，这能展示更深的理解。
Practise tracing pseudocode manually. Given a set of inputs, work through the code line by line, tracking variable values in a trace table. This is a common exam task where you must complete a partially filled trace table.
练习手动追踪伪代码。给定一组输入，逐行执行代码，在追踪表中记录变量值。这是一种常见考试任务，你必须完成部分填写好的追踪表。
5. Database Query Scenarios | 数据库查询场景
In a case study, you might be given a table structure and asked to write a query using a query-by-example grid or SQL-like syntax. CAIE often uses a grid with fields, table, sort, criteria, and show rows. You must select the correct fields, set criteria (e.g., `>=10` or `=”Fiction”`), and decide sort order.
在案例分析中，可能会给出表结构，并要求使用示例查询网格或类似SQL语法写一个查询。CAIE常使用包含字段、表、排序、条件和显示行的网格。你必须选择正确的字段，设置条件（如 `>=10` 或 `=”Fiction”`），并决定排序方式。
For an SQL-style question, you might be asked to write: `SELECT Title, Author FROM Books WHERE Genre = ‘Science’ AND Available = TRUE ORDER BY Title ASC;` Understand `SELECT`, `FROM`, `WHERE`, `ORDER BY` and `GROUP BY`. Know that `*` means all fields.
对于SQL风格的问题，可能要求你写出：`SELECT Title, Author FROM Books WHERE Genre = ‘Science’ AND Available = TRUE ORDER BY Title ASC;` 理解 `SELECT`、`FROM`、`WHERE`、`ORDER BY` 和 `GROUP BY`。知道 `*` 表示所有字段。
Always refer to the scenario’s table and field names exactly as given. Do not invent new names. For validation, a common case study might ask you to explain how to prevent invalid data entry in a field — you would mention data types, presence checks, range checks, format checks and lookup tables.
始终严格使用场景中给定的表名和字段名。不要自己编造。对于数据验证，常见的案例分析可能会让你解释如何防止字段中输入无效数据——你应该提及数据类型、存在检查、范围检查、格式检查和查找表。
6. Logic Gates and Truth Tables | 逻辑门与真值表
Case studies involving control systems or security systems often require logic circuits. You must be able to draw circuits using AND, OR, NOT, NAND and NOR gates, and construct truth tables. A typical scenario: ‘A safe opens only when two keys (A and B) are turned and the override switch (C) is OFF.’
涉及控制系统或安全系统的案例分析经常需要逻辑电路。你必须能够使用与门、或门、非门、与非门和或非门绘制电路，并构建真值表。一个典型场景：“仅当两把钥匙（A和B）都转动且越控开关（C）关闭时，保险箱才打开。”
Express this as a Boolean expression: Open = A AND B AND NOT C. Show the truth table with all combinations of A, B, C. Highlight the row where the output is 1. You may also be asked to simplify a logic statement using Boolean algebra or identify a single gate equivalent.
将其表示为布尔表达式：Open = A AND B AND NOT C。展示包含A、B、C所有组合的真值表。突出显示输出为1的那一行。也可能要求你使用布尔代数简化逻辑语句，或识别等效的单一门。
Use a systematic approach: list inputs in binary counting order. Remember NAND is the opposite of AND, NOR is the opposite of OR. When drawing circuits, always label inputs and outputs neatly. For a given case study, suggest how sensors and logic could be used to automate a process.
使用系统方法：按二进制计数顺序列出输入。记住与非门是与门的反相，或非门是或门的反相。绘制电路时，始终整齐标记输入和输出。对于给定的案例分析，可以建议如何使用传感器和逻辑来实现过程自动化。
7. Data Representation and Error Checking | 数据表示与错误校验
Case studies may describe a barcode system in a supermarket or a QR code for library books. You might be asked to explain how data is represented, such as how a number is converted to binary using place values. Show the calculation for a given decimal, e.g., 109₁₀ = 01101101₂ in 8-bit.
案例分析可能描述超市的条形码系统或图书馆书籍的二维码。你可能需要解释数据是如何表示的，比如如何利用位值将数字转换为二进制。展示给定十进制的计算，例如 109₁₀ = 01101101₂（8位）。
Error detection and correction are common topics. Explain parity checks: even parity adds a bit so the total number of 1s is even. Given a byte 1011001, even parity bit is 0 (it already has four 1s). For odd parity, bit would be 1. Check digits are used in ISBN and barcodes; you may be asked to calculate the check digit using a modulo-11 or modulo-10 algorithm.
错误检测和纠正是常见主题。解释奇偶校验：偶校验增加一位使得1的总数为偶数。给定字节1011001，偶校验位是0（已经有四个1）。奇校验位则为1。校验位用于ISBN和条形码；你可能需要根据模11或模10算法计算校验位。
Another scenario could involve analogue to digital conversion: sampling rate and resolution. Explain that higher sampling rate captures more detail but increases file size. Use the context — e.g., a sound recording of a school concert — to justify your recommendation.
另一个场景可能涉及模数转换：采样率和分辨率。解释更高的采样率能捕获更多细节，但会增加文件大小。结合上下文——例如学校音乐会的录音——来论证你的建议。
8. Cybersecurity Threats and Solutions | 网络安全威胁与解决方案
Case studies involving an online business or school network are an opportunity to discuss cybersecurity. You could be asked to identify threats such as phishing, malware, brute-force attacks, SQL injection and denial-of-service (DoS) attacks. Explain the nature of each threat and its potential impact on the organisation described.
涉及在线业务或学校网络的案例分析是讨论网络安全的好机会。你可能会被要求识别威胁，如网络钓鱼、恶意软件、暴力攻击、SQL注入和拒绝服务(DoS)攻击。解释每种威胁的性质及其对所述组织的潜在影响。
Then propose appropriate prevention or mitigation strategies: firewalls, anti-malware software, intrusion detection systems, encryption, access rights, two-factor authentication and regular backups. Always link your solutions to the scenario — e.g., ‘The school should enforce a strong password policy and educate staff about phishing emails because the case states that teachers frequently access sensitive student data from home.’
然后提出适当的预防或缓解策略：防火墙、反恶意软件、入侵检测系统、加密、访问权限、双因素认证和定期备份。一定要将解决方案与场景联系起来——例如，“学校应执行强密码策略并教育员工防范钓鱼邮件，因为案例指出教师经常在家访问敏感的学生数据。”
You might be asked to evaluate the consequences of a data breach, including legal implications under data protection laws. Be specific: mention fines, reputation damage, and loss of trust. Use technical terms accurately.
你可能需要评估数据泄露的后果，包括数据保护法下的法律影响。具体说明：罚款、声誉损害和信任丧失。准确使用专业术语。
9. Ethical and Legal Considerations | 伦理与法律考量
Many case studies include an element of ethical or legal decision-making — perhaps a fitness app collecting users’ health data, or a school using facial recognition for attendance. You must discuss the benefits of the system balanced against privacy concerns, consent, and data security.
许多案例分析包含伦理或法律决策元素——可能是健身应用收集用户健康数据，或学校使用面部识别考勤。你必须讨论系统的益处，同时权衡隐私问题、知情同意和数据安全。
Key legislation includes the Data Protection Act (or GDPR-equivalent principles) and the Computer Misuse Act. Explain that personal data must be processed lawfully, used only for the stated purpose, kept secure, and not kept longer than necessary. Hacking or unauthorised access is a criminal offence.
关键立法包括数据保护法（或GDPR等同原则）和计算机滥用法。解释个人数据必须合法处理、仅用于声明目的、安全保存且保存时间不超过必要。黑客攻击或未授权访问属于刑事犯罪。
When evaluating a system’s impact, consider stakeholders: students, parents, teachers, management. Discuss potential cultural, social and economic effects. Show a balanced argument and conclude with a justified opinion.
评估系统影响时，考虑利益相关者：学生、家长、教师、管理层。讨论潜在的文化、社会和经济影响。展示平衡的论点，并以有理由的观点作结。
10. System Analysis and Design | 系统分析与设计
If the case study describes a need for a new information system, you might need to describe the stages of the system life cycle: analysis, design, development/testing, implementation, documentation and evaluation. Outline requirements-gathering techniques such as interviews, questionnaires and observation of current practices.
如果案例分析描述了新信息系统需求，你可能需要描述系统生命周期的各个阶段：分析、设计、开发/测试、实施、文档编制和评估。概述需求收集技术，如访谈、问卷调查和观察现行做法。
For design, discuss user interface (usability considerations, consistency), data structures (e.g., records in a database), and processing. A data flow diagram (DFD) or system flowchart may be required. Use appropriate symbols and label data stores, processes and external entities.
对于设计，讨论用户界面（可用性考量、一致性）、数据结构（如数据库中的记录）和处理过程。可能需要数据流图（DFD）或系统流程图。使用适当符号，标记数据存储、处理过程和外部实体。
When evaluating a proposed system, mention feasibility and test strategies. Accept that some answers may require you to justify the choice between off-the-shelf and custom-written software based on the scenario’s budget and uniqueness of tasks.
评估提议系统时，提及可行性和测试策略。请注意有些答案可能需要你根据场景的预算和任务独特性，论证选择现成软件还是定制软件的理由。
11. Exam Tips for Case Study Questions | 案例分析题的考试技巧
Read the preamble and all sub-questions before starting. Highlight key words: ‘explain’, ‘suggest’, ‘justify’, ‘complete’. Pay attention to mark allocations — a 4-mark question should have four distinct points. Use technical vocabulary but ensure it is correctly applied to the context.
开始答题前通读引言和所有子问题。标出关键词：“解释”、“建议”、“论证”、“完成”。注意分值——一道4分的题目应有四个不同的点。使用专业词汇，但要确保正确应用于上下文。
Manage your time. Do not spend too long on a single diagram or table. If you get stuck, move on and return. For ‘evaluate’ questions, construct a mini-essay: advantages, disadvantages, and a conclusion linked back to the scenario.
管理时间。不要在一个图或表上花费过多时间。如果卡住，继续往下做，之后再回来。对于“评估”题，构建一个小短文：优点、缺点，以及与场景相联系的总评。
When using examples from the case, quote specifics: ‘the library uses barcode scanners to track books’ rather than a vague ‘the library has technology’. Originality and precision demonstrate high-level application.
使用案例中的例子时，引用具体细节：“图书馆用条形码扫描器追踪图书”，而不是含糊的“图书馆有技术”。独创性和精确性展现了高级应用能力。
12. Practice Case Study: School Library System | 实战案例：学校图书馆系统
Scenario: Greenfield High School wants to computerise its library. Books are lent to students for two weeks. After that, a fine of $0.30 per day is charged. The librarian must be able to add new books, record loans and returns, view which students have overdue books, and generate reports of most borrowed genres. The system must be accessible from library computers and via a web portal for students to renew books.
场景： 格林菲尔德高中希望将其图书馆计算机化。图书借给学生两周。逾期每天罚款0.30美元。图书管理员必须能够添加新书、记录借还、查看哪些学生有逾期图书，并生成借阅最多的图书类型报告。系统必须能从图书馆电脑访问，也通过门户网站供学生续借图书。
Now let’s apply our skills to this case study. We will decompose the system, design a simple algorithm for overdue calculation, suggest a database structure, and discuss security measures.
现在让我们将技能应用到这个案例中。我们将分解系统，设计逾期计算的简单算法，建议数据库结构，并讨论安全措施。
Decomposition: The library system can be split into modules: Student Management, Book Inventory, Loan Processing, Fine Calculation, Report Generation, and Web Portal Interface. Data flows: Student details and Loan records to Fine Calculation, Book IDs to Loan Processing.
问题分解： 图书馆系统可拆分为模块：学生管理、图书库存、借阅处理、罚款计算、报告生成和门户网站界面。数据流：学生详细信息和借阅记录流向罚款计算，图书ID流向借阅处理。
Algorithm — Calculate Fine:
算法 — 计算罚款：
Pseudocode:
INPUT BookID, StudentID, ReturnDate
DueDate = LoanDate + 14
IF ReturnDate > DueDate THEN
DaysLate = ReturnDate - DueDate
Fine = DaysLate * 0.30
ELSE
Fine = 0
ENDIF
OUTPUT "Fine for ", BookID, " is $", Fine
A truth table for a simple logic extension: If a student has both an overdue book AND an outstanding fine over $5, they cannot renew. This could be implemented with an AND gate: BlockRenew = Overdue AND (Fine > 5).
一个简单逻辑扩展的真值表：如果学生既有逾期图书且未缴罚款超过$5，则不能续借。这可以用与门实现：BlockRenew = Overdue AND (Fine > 5)。
The system will use a relational database. A possible table structure:
系统将使用关系数据库。可能的表结构：
| Table | Fields |
|---|---|
| Students | StudentID (PK), Name, Form, Email |
| Books | BookID (PK), Title, Author, ISBN, Genre, AvailableCopies |
| Loans | LoanID (PK), BookID (FK), StudentID (FK), LoanDate, ReturnDate, FinePaid |
Query to find all students with overdue books:
查询所有逾期图书的学生：
SELECT Students.Name, Books.Title, Loans.LoanDate FROM Students INNER JOIN Loans ON Students.StudentID = Loans.StudentID INNER JOIN Books ON Loans.BookID = Books.BookID WHERE Loans.ReturnDate IS NULL AND Loans.LoanDate < DATEADD(DAY, -14, GETDATE());
Security considerations: The web portal must use HTTPS to encrypt login credentials. Librarian access should require two-factor authentication. The server room should be physically secured. Regular backups of the database will protect against data loss.
安全考量：门户网站必须使用HTTPS加密登录凭证。图书管理员访问应要求双因素认证。服务器机房应有物理安全防护。定期备份数据库防止数据丢失。
This practice case shows how multiple syllabus topics integrate into one realistic scenario. By working through similar examples, you will become confident in handling any case study question in your exam.
这个实战案例展示了多个考纲主题如何整合到一个现实场景中。通过练习类似例子，你将充满信心地应对考试中的任何案例分析题。
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