📚 Year 9 SQA Computing: Case Study Practical Exercises | 九年级 SQA 计算机：案例分析实战演练
Case studies are a powerful way to develop practical computing skills. By working through a real-world scenario, you learn to analyse problems, design solutions, implement code, and test your program -- just like a professional software developer. This article presents a full case study for Year 9 SQA Computing, guiding you step by step through building a Movie Age-Rating Advisor. You will practise computational thinking, flowchart design, pseudocode, Python and Scratch implementation, testing and evaluation.
案例研究是培养实用计算机技能的有效方式。通过解决一个真实场景的问题，你会学习分析需求、设计解决方案、编写代码和测试程序——就像专业软件开发人员一样。本文为九年级 SQA 计算机课程提供一个完整的案例实战演练，引导你逐步构建一个电影年龄分级顾问程序。你将练习计算思维、流程图设计、伪代码以及 Python 和 Scratch 的实现、测试与评估。
1. Introduction to Case Studies in Computing | 计算机案例研究简介
In SQA Computing, case studies help you demonstrate problem-solving and programming abilities. You are often given a brief description of a software need and asked to produce a working solution. The process involves understanding the problem, identifying inputs, processes and outputs, planning an algorithm, writing code and testing thoroughly.
在 SQA 计算机课程中，案例研究帮助你展示问题解决和编程能力。你通常会拿到一份软件需求简述，需要给出一个可运行的解决方案。整个过程包括理解问题、识别输入、处理和输出、规划算法、编写代码并进行充分测试。
The skills you develop here are not just for exams -- they mirror what programmers do every day. By treating a simple project as a case study, you build a structured approach that will serve you well in more complex tasks later.
你在这里培养的技能不仅用于考试——它们反映了程序员每天的工作方式。把一个简单项目当作案例来研究，你就能建立一种结构化的思维方法，这对日后处理更复杂的任务大有益处。
2. The Problem Statement: Movie Rating Advisor | 问题陈述：电影年龄分级顾问
Your task is to design a program that asks for the user' priate UK film rating they are allowed to watch. The rating rules are: under 8 years old → 'U'; 8 to 11 → 'PG'; 12 to 14 → '12A'; 15 to 17 → '15'; 18 and over → '18'. The program must give a clear message such as 'You can watch films rated up to: 12A'.
你的任务是设计一个程序，询问用户的年龄，然后显示他们可以观看的相应英国电影分级。分级规则如下：年龄小于 8 → 'U'；8 至 11 岁 → 'PG'；12 至 14 岁 → '12A'；15 至 17 岁 → '15'；18 岁及以上 → '18'。程序必须给出明确的信息，例如“您可以观看的最高电影分级为：12A”。
This is a typical beginner-level problem that involves decision-making and conditional statements. It's perfect for practising how to convert a real-life rule into code logic. You will work through this problem from scratch, exactly as you would in a school assignment or an SQA assessment.
这是一个典型的初学者级别问题，涉及决策和条件语句。它非常适合练习如何将现实生活中的规则转换成代码逻辑。你将从头开始解决这个问题，完全按照学校作业或 SQA 评估的要求来做。
3. Requirements Analysis | 需求分析
Before writing any code, we must identify the inputs, process and outputs. Input: the user's age (a whole number). Process: compare the age against the rating boundaries using an if-elif-else structure. Output: a message stating the maximum permitted rating.
在编写任何代码之前，我们必须确定输入、处理和输出。输入：用户的年龄（一个整数）。处理：使用 if-elif-else 结构将年龄与分级界限进行比较。输出：显示一条说明最高允许分级的信息。
We also need to consider edge cases: what if the user enters a negative number or an age over 120? For a basic solution we can assume sensible input, but good practice means adding simple validation. For now, we will focus on the core logic and note validation as a future improvement.
我们还需要考虑边界情况：如果用户输入负数或年龄超过 120 岁怎么办？对于基础解决方案，我们可以假设输入是合理的，但良好的习惯意味着要添加简单的验证。目前我们专注于核心逻辑，把输入验证作为后续改进点记录下来。
4. Designing the Algorithm (Flowchart) | 算法设计（流程图）
A flowchart is a visual way of representing the decision-making process. It uses standard symbols: an oval for start/end, a parallelogram for input/output, and a diamond for decisions. For our Movie Advisor, the flowchart begins with 'Start', then 'Input age', followed by a series of decision diamonds checking age ranges.
流程图是展现决策过程的可视化方法。它使用标准符号：椭圆形表示开始/结束，平行四边形表示输入/输出，菱形表示判断。对于我们的电影顾问程序，流程图从“开始”开始，然后“输入年龄”，接着是一系列检查年龄段的条件判断菱形。
Example logic: age < 8 takes the 'Yes' branch to output 'U', then ends. If 'No', check age ≤ 11, output 'PG', and so on. The final path uses 'otherwise' to output '18' this flowchart helps you see the exact sequence of comparisons, making coding much easier.
示例逻辑：年龄 < 8 走“是”分支输出 'U'，然后结束。如果“否”，则检查年龄 ≤ 11，输出 'PG'，依此类推。最后一条路径用“否则”输出 '18'。画出这个流程图能帮你看清比较的准确顺序，让编码变得更简单。
5. Pseudocode for the Program | 程序的伪代码
Pseudocode is a half-code, half-English description of the algorithm. It does not follow strict syntax, allowing you to concentrate on logic. Here is the pseudocode for our Movie Rating Advisor:
伪代码是算法的半代码半自然语言描述。它不遵循严格的语法，让你能专注于逻辑本身。下面是我们电影分级顾问程序的伪代码：
START
OUTPUT "Enter your age:"
INPUT age
IF age < 8 THEN
rating ← "U"
ELSE IF age ≤ 11 THEN
rating ← "PG"
ELSE IF age ≤ 14 THEN
rating ← "12A"
ELSE IF age ≤ 17 THEN
rating ← "15"
ELSE
rating ← "18"
END IF
OUTPUT "You can watch films rated up to: " + rating
STOP
ages like 8 are caught in the PG range. The indentation shows the nested structure clearly, even though it is not formal code. Practising pseudocode will improve your planning skills for exams.
请注意每个条件是如何测试特定界限的。使用 ≤ 能确保像 8 岁这样的年龄被归入 PG 区间。缩进清楚地展示了嵌套结构，尽管这不是正式代码。练习伪代码能提高你在考试中的规划能力。
6. Coding the Solution in Python | 用 Python 编写解决方案
Python is one of the most popular languages in SQA Computing. The code below translates the pseudocode into working Python. Notice the use of input(), int() and print(), along with the if-elif-else statement.
Python 是 SQA 计算机课程中最受欢迎的语言之一。下面的代码将伪代码翻译为可运行的 Python。请注意 input()、int() 和 print() 的使用，以及 if-elif-else 语句。
age = int(input("Enter your age: "))
if age < 8:
rating = "U"
elif age <= 11:
rating = "PG"
elif age <= 14:
rating = "12A"
elif age <= 17:
rating = "15"
else:
rating = "18"
print("You can watch films rated up to:", rating)This code is clear and efficient. The elif chain evaluates conditions from top to bottom, so we must order the checks carefully. A common mistake is to check higher bounds first; doing so would break the logic. Test it with ages 0, 7, 8, 14, 17 and 18 to verify correctness.
这段代码清晰高效。elif 链从上到下依次评估条件，所以我们必须仔细排列检查的顺序。一个常见的错误是先检查较大的边界，那样会破坏逻辑。用 0、7、8、14、17 和 18 岁的年龄来测试，以验证正确性。
7. Coding the Solution in Scratch | 用 Scratch 编码解决方案
Scratch is often used in early secondary computing. The same logic can be built using blocks. You would create a variable 'age' and use 'ask and wait' to get input. Then, a series of 'if … then … else' control blocks compares the age. The 'say' block outputs the result.
Scratch 常用于中学低年级的计算机课程。相同的逻辑可以用积木块来实现。你需要创建一个变量“age”，用“询问并等待”来获取输入。然后用一系列“如果 … 那么 … 否则”控制块来比较年龄。用“说”积木输出结果。
Because Scratch doesn't have an explicit elif, you nest 'if … else' blocks inside each other. The first checks 'if age < 8', else inside check 'if age < 12', and so on. Finally, an 'else' handles age ≥ 18. This visual approach reinforces the decision tree concept.
因为 Scratch 没有明确的 elif，你需要将“如果 … 否则”积木相互嵌套。第一个检查“如果 age < 8”，否则在内部检查“如果 age < 12”，依此类推。最后，一个“否则”处理年龄 ≥ 18。这种可视化方法强化了决策树的概念。
Learning to implement the same algorithm in both text-based and block-based environments is a valuable skill. It demonstrates that you understand the underlying computational thinking, not just the syntax.
学会在文本环境和积木环境中实现相同的算法是一项宝贵技能。它表明你理解背后的计算思维，而不仅仅是语法。
8. Test Plan and Debugging | 测试计划与调试
A thorough test plan is essential. You should test boundary values and typical values. Create a table to record expected and actual outputs. Here is an example test table:
制定一份详尽的测试计划至关重要。你应该测试边界值和典型值。创建一个表格来记录预期输出和实际输出。以下是一个测试表示例：
| Test No. | Input Age | Expected Rating | Actual Rating | Pass/Fail |
|---|---|---|---|---|
| 1 | 5 | U | ||
| 2 | 8 | PG | ||
| 3 | 11 | PG | ||
| 4 | 12 | 12A | ||
| 5 | 14 | 12A | ||
| 6 | 15 | 15 | ||
| 7 | 17 | 15 | ||
| 8 | 18 | 18 | ||
| 9 | 25 | 18 |
Fill in the actual results when you run the program. If any test fails, debug by checking the order of conditions and the operators used. Remember, the tests for boundaries are the most likely to reveal off-by-one errors.
运行程序时填入实际结果。如果任何测试失败，通过检查条件顺序和使用的运算符来进行调试。请记住，边界测试最容易暴露差一错误。
9. Evaluation of the Solution | 解决方案评估
After testing, evaluate your program against the original requirements. Does it correctly output the maximum permitted rating for any valid age? Is the user message clear and helpful? Are there any limitations?
测试之后，根据最初的需求评估你的程序。它是否能为任何有效年龄正确输出允许的最高分级？用户提示信息是否清晰有用？是否存在局限性？
One limitation is the lack of input validation -- if the user types 'twelve' or a negative number, the program crashes or gives a wrong rating. To improve, you could add a loop that repeatedly asks for age until a valid integer is entered. This real-world adjustment shows deeper understanding.
一个局限性是缺少输入验证——如果用户输入“twelve”或负数，程序会崩溃或给出错误分级。为了改进，你可以添加一个循环，反复询问年龄直到输入有效的整数。这种贴近实际的调整能体现你对问题更深的理解。
Evaluation is an important part of SQA assignments; you should be able to suggest at least two refinements. Reflecting on what you have built reinforces learning and prepares you for more advanced projects.
评估是 SQA 作业的重要部分；你应该能够提出至少两项改进建议。反思你所构建的程序可以巩固学习，并为更高级的项目做好准备。
10. Extending the Program with a Loop | 使用循环扩展程序
Let's enhance the program to ask for multiple users until the user decides to quit. We can wrap the main logic inside a while loop. In Python, we would add a 'while True' loop and break when the user types 'quit'.
让我们改进这个程序，使其能够询问多个用户，直到用户决定退出。我们可以将主逻辑放在一个 while 循环中。在 Python 中，可以添加一个“while True”循环，并在用户输入“quit”时中断。
This improves the user experience and demonstrates your ability to handle repetition and termination conditions. Such an extension is easy to test and adds value to the case study, showing that you can think beyond the minimum requirements.
这改善了用户体验，并展示了处理重复和终止条件的能力。这样的扩展很容易测试，并为案例研究增加了价值，表明你可以超越最低要求进行思考。
Always document the change: explain why the loop was added and how it works. This commentary is exactly what an SQA marker looks for to award higher marks for evaluation and development.
始终记录这些修改：解释为什么要添加循环以及它是如何工作的。这些评注正是 SQA 评分员在评价开发与评估环节时，用来给出更高分数的依据。
11. Common Errors and Troubleshooting | 常见错误及故障排除
in Python, which causes a syntax error. Another is reversing the order of boundary checks, leading to a younger age receiving an 18 rating.
学生在编写条件语句时经常出错。一个常见错误是在 Python 中用 = 代替 ==，导致语法错误。另一个错误是颠倒了边界检查的顺序，导致较小年龄获得 18 级的评级。
In Scratch, forgetting to convert the answer from a text string to a number can cause the comparisons to behave unexpectedly. Always use a 'set age to answer' and ensure the variable is treated as a number. Practising these troubleshooting steps builds resilience and debugging skills.
在 Scratch 中，忘记将答案从文本字符串转换为数字会导致比较行为异常。务必使用“将 age 设为回答”并确保该变量作为数字处理。练习这些故障排除步骤可以培养应对错误的能力和调试技巧。
Keep a log of errors you encounter and how you fixed them. This habit turns every mistake into a learning opportunity and prepares you for the independent problem-solving required in assessments.
记录下你遇到的错误以及你是如何修复的。这个习惯能把每一个错误都转化为学习机会，并为你应对评估中所需的独立解决问题能力做好准备。
12. Conclusion and Revision Tips | 总结与复习建议
This case study has walked you through the full computing development cycle: from problem analysis and design to implementation, testing and evaluation. You have seen the same logic expressed in pseudocode, Python and Scratch, which reinforces your programming knowledge for SQA Computing.
本案例研究带你走过了完整的计算机开发周期：从问题分析和设计，到实现、测试和评估。你看到了相同的逻辑用伪代码、Python 和 Scratch 表达出来，这强化了你对 SQA 计算机课程的编程知识。
For revision, try modifying the rating rules to create a different advisor (e.g., game age ratings PEGI). Draw the new flowchart, write pseudocode, and code it independently. The more you practise building small case studies, the more confident you will become for your exams.
作为复习，试着修改分级规则，创建一个不同的顾问程序（例如 PEGI 游戏年龄评级）。画出新的流程图，编写伪代码并独立实现。你越多地练习构建小型案例研究，你就会对考试越有信心。
Remember, computing is about thinking logically and breaking problems into manageable parts. Every case study you complete sharpens that skill. Good luck with your SQA Computing journey!
请记住，计算就是逻辑思考和将问题分解成可管理的部分。你完成的每个案例研究都会磨练这项技能。祝你在 SQA 计算机的学习旅程中好运！
Published by TutorHao | Computing Revision Series | aleveler.com
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