📚 Case Study in Practice | 案例分析实战演练
In Year 7 CAIE Computer Science, learning to solve problems step by step is a vital skill. One of the best ways to develop this skill is by working through a case study – a detailed look at a real or imaginary situation that needs a computing solution. This article will guide you through the key stages of analysing and solving a computer-based case study, using a simple example to help you understand each stage clearly.
在 Year 7 CAIE 计算机科学中，逐步解决问题的能力至关重要。培养这一技能的最佳方式之一就是进行案例分析——详细分析一个需要计算机解决方案的真实或虚构的场景。本文将带你了解分析和解决计算机案例的关键阶段，并用一个简单的例子帮助你清晰地理解每个阶段。
1. What is a Case Study in Computing? | 什么是计算机案例分析？
A case study in computing is a scenario that describes a problem or a need that can be addressed using technology. It usually involves a user, a context, and a set of requirements. By studying the case, you learn to identify what the system must do and how it can be built.
计算机中的案例分析是描述一个可以用技术解决的问题或需求的场景。它通常涉及用户、背景和一组需求。通过研究案例，你学会识别系统必须做什么以及如何构建它。
2. Why Practice with Case Studies? | 为什么要练习案例分析？
Practising case studies helps you think like a computer scientist. You will learn to break down complex problems, spot patterns, design algorithms, and test solutions. This is exactly what you need for your CAIE exams and for real-world programming tasks.
练习案例分析有助于像计算机科学家一样思考。你将学会分解复杂问题、发现模式、设计算法并测试解决方案。这正是 CAIE 考试和现实编程任务所需要的能力。
3. Step 1 – Understand the Problem | 第一步——理解问题
Before you jump into coding, read the case study carefully. Highlight keywords, note the users, and list what the system is supposed to do. Ask yourself: 'What is the goal?' and 'Who will use it?'.
在动手编码之前，请仔细阅读案例。标出关键词，记录用户，并列出系统应该做什么。问自己：“目标是什么？”以及“谁会使用它？”。
4. Step 2 – Decompose the Problem | 第二步——分解问题
Decomposition means breaking a large problem into smaller, more manageable parts. For example, if the case study asks for a quiz app, you can split it into: login, question display, scoring, and feedback. Tackling one piece at a time makes the task easier.
分解意味着将一个大问题拆分成更小、更容易管理的部分。例如，如果案例要求设计一个问答应用，你可以将其拆分为：登录、题目显示、计分和反馈。每次处理一个部分会使任务更简单。
5. Step 3 – Identify Inputs, Processes, and Outputs | 第三步——确定输入、处理和输出
Every computer system works with data. Identify what data will go in (inputs), what the system will do with it (processes), and what comes out (outputs). This model forms the backbone of your solution.
每个计算机系统都处理数据。确定哪些数据将进入（输入）、系统将如何处理这些数据（处理）以及会出现什么结果（输出）。这个模型构成了解决方案的骨架。
6. Step 4 – Design the Solution Using Pseudocode | 第四步——使用伪代码设计解决方案
Pseudocode is a way to write an algorithm in simple, English-like statements. It is not a real programming language but helps you plan your logic. Use clear words like INPUT, OUTPUT, IF…THEN…ELSE, and loops like REPEAT or WHILE.
伪代码是一种用简单的、类似英语的语句编写算法的方式。它不是真正的编程语言，但有助于规划逻辑。使用清晰的关键词，如 INPUT、OUTPUT、IF…THEN…ELSE 以及 REPEAT 或 WHILE 等循环。
7. Step 5 – Draw a Flowchart | 第五步——绘制流程图
A flowchart uses standard symbols to show the flow of steps. Ovals for start/end, rectangles for processes, diamonds for decisions, and parallelograms for input/output. Drawing a flowchart can reveal missing steps or errors in your logic.
流程图使用标准符号来展示步骤的流程。椭圆形表示开始/结束，矩形表示处理过程，菱形表示决策，平行四边形表示输入/输出。绘制流程图可以揭示逻辑中缺失的步骤或错误。
8. Introducing a Case Study: The Simple Calculator | 案例引入：简单计算器
Now let's apply these steps to a concrete example. The case study is: 'A teacher wants a program for primary students that can add, subtract, multiply, or divide two numbers. The user chooses the operation and enters two numbers. The program then shows the result.'
现在让我们将这些步骤应用到一个具体例子。案例是：“一位老师想要一个面向小学生的程序，可以进行两个数的加、减、乘、除运算。用户选择运算并输入两个数字，程序然后显示结果。”
9. Understanding the Calculator Problem | 理解计算器问题
an operator symbol (+, -, ×, ÷) and two numeric values, then calculate and display the answer.
首先，我们理解目标：执行基本算术运算。用户是小学生，因此界面应该简单。系统必须接受一个运算符（+、-、×、÷）和两个数值，然后计算并显示答案。
10. Designing the Calculator Solution | 设计计算器解决方案
Decomposition: we need input of operator and numbers, decision of which operation to do, calculation, and output. The IPO (Input-Process-Output) chart looks like this:
分解：我们需要输入运算符和数字，决定执行哪种运算，进行计算，然后输出。IPO（输入-处理-输出）表如下：
| Input | Process | Output |
|---|---|---|
| operator, num1, num2 | Decide which mathematical operation to perform; calculate result | result |
（中文对应：输入：运算符，数字1，数字2；处理：判断执行哪种数学运算；计算结果；输出：结果。）
Now we write pseudocode:
OUTPUT "Enter operator (+, -, *, /): "
INPUT operator
OUTPUT "Enter first number: "
INPUT num1
OUTPUT "Enter second number: "
INPUT num2
IF operator = "+" THEN
result = num1 + num2
ELSE IF operator = "-" THEN
result = num1 - num2
ELSE IF operator = "*" THEN
result = num1 * num2
ELSE IF operator = "/" THEN
IF num2 ≠ 0 THEN
result = num1 ÷ num2
ELSE
OUTPUT "Error: Cannot divide by zero"
END IF
ELSE
OUTPUT "Invalid operator"
END IF
OUTPUT "Result: ", result
现在写出伪代码（中文对应）：首先输出提示，输入运算符和两个数，用 IF 判断运算类型，注意除法时分母不能为零，最后输出结果。
11. Testing and Debugging | 测试与调试
., 5 ÷ 0). Trace your algorithm with each set and check the outputs. Debug any errors found.
测试确保程序按预期工作。准备测试数据：正常数据（如 5+3=8）、边界数据（如 0÷5=0）和错误数据（如 5÷0）。用每组数据跟踪算法并检查输出。调试发现的任何错误。
12. Evaluation and Real-World Connection | 评估与真实世界联系
Finally, evaluate your solution. Does it meet the teacher's request? Is it easy for primary students? Could it be improved, for example by adding a loop so the user can do many calculations without restarting? Case studies help you see not just the code but the whole problem-solving cycle.
最后，评估你的解决方案。它满足老师的要求吗？对小学生来说容易吗？可以改进吗，例如添加一个循环，让用户无需重新启动即可进行多次计算？案例分析帮助你看清不仅仅是代码，而是整个解决问题的周期。
Published by TutorHao | Computer Science Revision Series | aleveler.com
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