📚 Case Study Practical Exercises for CCEA Year 11 Computing | CCEA 11 年级计算机：案例分析实战演练
A case study in computing is a detailed investigation of a real‑world problem that requires a programmed solution. It tests your ability to break down a scenario, identify inputs, processes, and outputs, design algorithms, and consider evaluation criteria—exactly the skills assessed in CCEA’s Year 11 practical programming tasks and written papers. This article provides a structured approach to tackling case studies, with worked examples and practice tasks.
计算机中的案例分析是对需要编程解决的真实世界问题进行详细研究。它考查你将场景分解、识别输入、处理和输出、设计算法并考虑评估标准的能力——正是 CCEA 11 年级实践编程任务和笔试中评估的技能。本文提供一种结构化的案例分析方法，包含已解答的示例和练习任务。
1. Understanding the Case Study Brief | 理解案例分析题目
A CCEA case study brief will describe a situation, often including user requirements, constraints, and a narrative about a client. Read it several times and highlight key nouns (possible data items) and verbs (possible processes). Ask: What is the problem? Who is the user? What must the program achieve?
CCEA 案例分析题目会描述一个情境，通常包含用户需求、限制条件和客户叙述。多读几遍，标出关键名词（可能的数据项）和动词（可能的处理过程）。问自己：问题是什么？用户是谁？程序必须实现什么目标？
Example brief extract: “A local library needs a system to track book loans. Members borrow up to three books at a time. Books are identified by a barcode. The system must record loan dates and calculate fines for late returns at 20p per day.”
示例摘录：“本地图书馆需要一个系统来跟踪图书借阅。会员一次最多可借三本书。图书通过条形码识别。系统必须记录借阅日期并计算逾期还书的罚款（每天 20 便士）。”
2. Identifying Inputs, Processes, and Outputs (IPO) | 识别输入、处理和输出（IPO）
The IPO model is the foundation of any solution. List all inputs (data entering the system), processes (actions performed), and outputs (information displayed or stored). Use a table to keep it organised.
IPO 模型是任何解决方案的基础。列出所有输入（进入系统的数据）、处理（执行的操作）和输出（显示或存储的信息）。使用表格保持条理。
| Inputs | Processes | Outputs |
|---|---|---|
| Member ID Book barcode Loan date Return date |
Validate membership Check book availability Calculate overdue days Compute fine Update loan records |
Loan confirmation message Overdue fine amount Updated inventory status Member loan history report |
3. Breaking Down the Problem into Manageable Parts | 将问题分解为可管理的部分
Decomposition is a key computational thinking skill. Split the main problem into smaller sub‑problems—each can be solved independently. For the library system, sub‑problems might include: borrower validation, book stock checking, loan recording, fine calculation, and reporting.
分解是一项关键的计算思维技能。将主要问题拆分成较小的子问题——每个可以独立解决。对于图书馆系统，子问题可能包括：借阅者验证、图书库存检查、借阅记录、罚款计算和报表生成。
Structure your sub‑problems in a hierarchical list so you can address one at a time, turning them later into separate functions or modules.
以层级列表的形式构建子问题，以便逐一处理，稍后可将它们转换为独立的函数或模块。
4. Designing Algorithms with Pseudocode | 用伪代码设计算法
Pseudocode bridges the gap between human language and code. Use CCEA‑exam‑style pseudocode conventions: consistent indentation, capitalised keywords like IF, THEN, ELSE, WHILE, ENDWHILE, FOR, ENDFOR, INPUT, OUTPUT. Be precise but not language‑specific.
伪代码弥合了人类语言与代码之间的差距。使用 CCEA 考试风格的伪代码约定：一致缩进，大写关键字如 IF、THEN、ELSE、WHILE、ENDWHILE、FOR、ENDFOR、INPUT、OUTPUT。表述精确但不特定于某种编程语言。
Example pseudocode for fine calculation:
罚款计算伪代码示例：
INPUT daysLate
IF daysLate > 0 THEN
fine ← daysLate * 0.20
ELSE
fine ← 0
ENDIF
OUTPUT fine
5. Flowcharts as Visual Representations | 流程图作为可视化表示
Flowcharts help you trace logic visually before coding. Use standard symbols: oval for start/stop, parallelogram for input/output, rectangle for process, diamond for decision. Draw arrows to show the flow of control. Ensure loops and decisions are clear.
流程图帮助你在编码前直观地追踪逻辑。使用标准符号：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、菱形表示判断。用箭头表示控制流程。确保循环和判断清晰。
Decision symbol in text: “Is daysLate > 0?” → Yes branch leads to fine calculation; No branch sets fine = 0. Merge branches before output.
文本中的判断符号：“daysLate > 0 吗？”→ 是分支进入罚款计算；否分支设置 fine = 0。在输出前合并分支。
6. Choosing Data Types and Variables | 选择数据类型和变量
Select appropriate data types for each variable: INTEGER for whole numbers (e.g., daysLate), REAL or FLOAT for money (fine), STRING for text (memberName), BOOLEAN for true/false flags (isValid). Define constants for fixed values like FINE_RATE = 0.20.
为每个变量选择合适的数据类型：INTEGER 用于整数（如 daysLate），REAL 或 FLOAT 用于货币（fine），STRING 用于文本（memberName），BOOLEAN 用于真/假标志（isValid）。为固定值（如 FINE_RATE = 0.20）定义常量。
Use meaningful names that reveal purpose, e.g., overdueDays rather than d. This aids readability and debugging.
使用揭示目的的命名，如 overdueDays 而非 d。这有助于可读性和调试。
7. Incorporating Validation and Error Handling | 引入验证和错误处理
Defensive design is vital in case studies. Plan for invalid inputs: non‑numeric where a number is expected, out‑of‑range values, or data that doesn’t match expected formats. Use loops to re‑prompt until valid data is entered.
防御性设计在案例分析中至关重要。计划处理无效输入：期望数字却输入非数字、超出范围的值或不符合预期格式的数据。使用循环重新提示，直到输入有效数据。
Validation pseudocode structure:
验证伪代码结构：
REPEAT
INPUT amount
IF amount < 0 THEN
OUTPUT “Invalid, enter a positive number”
ENDIF
UNTIL amount >= 0
8. Testing Strategies and Test Plans | 测试策略和测试计划
Testing provides evidence your solution works. Design a test plan with normal, boundary, and erroneous data. List test ID, test data, expected result, actual result, and a comment. Boundary tests are crucial: for the fine rule, test daysLate = 0, 1, 10, and also negative values.
测试提供解决方案有效的证据。设计包括正常、边界和错误数据的测试计划。列出测试 ID、测试数据、预期结果、实际结果和备注。边界测试至关重要：对于罚款规则，测试 daysLate = 0、1、10，以及负值。
| Test ID | Data | Expected | Type |
|---|---|---|---|
| 1 | 3 days late | £0.60 | Normal |
| 2 | 0 days late | £0.00 | Boundary |
| 3 | -5 days late | Error message | Erroneous |
9. Iterative Development and Refinement | 迭代开发与优化
Case study solutions evolve through multiple versions. Start with a simple working prototype (e.g., fine calculation with fixed inputs), then add features: file reading for member data, a menu system, or output formatting. Reflect on what works and what can be improved after each iteration.
案例分析解决方案通过多个版本演进。从一个简单的工作原型开始（例如，使用固定输入计算罚款），然后添加功能：读取会员数据的文件、菜单系统或输出格式化。每次迭代后反思哪些有效、哪些可以改进。
Document changes and reasons; CCEA questions may ask you to justify design decisions.
记录更改和原因；CCEA 题目可能要求你证明设计决策的合理性。
10. Considering Usability and User Interface | 考虑可用性和用户界面
Even in text‑based programs, the user experience matters. Design clear prompts, informative error messages, and well‑formatted outputs. If the case study mentions non‑technical users, mention how your interface reduces confusion—perhaps by using numbered menus or consistent wording.
即使在基于文本的程序中，用户体验也很重要。设计清晰的提示、信息丰富的错误消息和格式良好的输出。如果案例分析提到非技术用户，说明您的界面如何减少困惑——也许通过使用编号菜单或一致的用语。
Example menu output:
菜单输出示例：
1. Borrow a book
2. Return a book
3. View member loans
4. Exit
Please choose an option:
11. Worked Practice: School Canteen Queue System | 实战练习：学校食堂排队系统
Let’s apply the approach to a new case: “Design a program to manage the lunch queue. Students enter their ID; the system checks if they have sufficient credit (≥£2.50) and deducts the cost of a meal deal. If credit is low, display the balance and suggest a top‑up. Queue length is limited to 30.”
让我们将这个方法应用到一个新案例：“设计一个管理午餐队列的程序。学生输入其 ID；系统检查他们是否有足够的余额（≥2.50 英镑），并扣除套餐费用。如果余额不足，显示余额并建议充值。队列长度限制为 30。”
First, IPO breakdown: inputs (student ID, current credit from stored data), processes (verify ID, check balance, deduct, update storage, manage queue length), outputs (meal approval or rejection message, new balance, queue status).
首先，IPO 分解：输入（学生 ID、来自存储数据的当前余额），处理（验证 ID、检查余额、扣款、更新存储、管理队列长度），输出（用餐批准或拒绝消息、新余额、队列状态）。
Then design sub‑problems: ID validation, credit check, deduction logic, queue counter, and a loop to accept next student until queue is full or manually exited.
然后设计子问题：ID 验证、余额检查、扣款逻辑、队列计数器，以及一个循环用于接受下一位学生，直到队列满员或手动退出。
12. From Case Study to Mark‑Winning Answers | 从案例分析到高分答案
In CCEA exams, case study questions often ask you to “justify” choices. Always link justification back to user needs, system constraints, or programming principles like efficiency, maintainability, or readability. Use technical vocabulary: decomposition, abstraction, IPO, variable scope, iteration, validation.
在 CCEA 考试中，案例分析题常要求你“论证”选择。始终将论证与用户需求、系统限制或编程原则（如效率、可维护性或可读性）联系起来。使用技术词汇：分解、抽象、IPO、变量作用域、迭代、验证。
Practice timed planning: read the brief (5 mins), list IPO (5 mins), sketch pseudocode or flowchart (10 mins), design test plan (5 mins), and write a short evaluation (5 mins). The more structured your preparation, the easier exam tasks become.
练习定时规划：阅读题目（5 分钟），列出 IPO（5 分钟），草拟伪代码或流程图（10 分钟），设计测试计划（5 分钟），并写简短评估（5 分钟）。你的准备越有结构，考试任务就越轻松。
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