Case Study Practical Workout | 案例分析实战演练

📚 Case Study Practical Workout | 案例分析实战演练

Welcome to this hands-on case study, designed to strengthen your understanding of key Year 8 Edexcel Computer Science concepts. You will step into the role of a consultant and solve a realistic technology challenge for a school. Through analysis, design, and evaluation, you will apply knowledge of networks, data security, binary representation, and simple algorithms.

欢迎来到这个实战案例研究，旨在加深你对八年级Edexcel计算机科学关键概念的理解。你将扮演顾问的角色，为学校解决一个真实的技术挑战。通过分析、设计和评估，你将应用网络、数据安全、二进制表示和简单算法的知识。

1. Case Introduction | 案例介绍

Greenfield School is planning to upgrade its computer lab to support modern teaching methods. The lab will house 30 student workstations, one teacher computer, a file server, and a shared printer. All devices must connect to the internet, share files efficiently, and protect sensitive student data. Additionally, the school needs a simple program to convert exam marks into letter grades and to sort student results for reporting. You have been hired to design this system and produce a detailed report.

格林菲尔德学校计划升级其计算机实验室，以支持现代教学方法。实验室将容纳30台学生工作站、一台教师电脑、一台文件服务器和一台共享打印机。所有设备必须连接互联网，高效共享文件，并保护敏感的学生数据。此外，学校需要一个简单的程序将考试分数转换成字母等级，并对学生成绩进行排序以便报告。你被聘请来设计这个系统并撰写一份详细报告。

2. Identifying User Needs | 确定用户需求

Before any design work, clear requirements must be listed. The primary needs for the lab upgrade and software are:

在任何设计工作之前，必须列出明确的需求。实验室升级和软件的主要需求如下：

A reliable network that allows all 31 computers to share the fileserver and printer, and access the internet simultaneously.

一个可靠的网络，使31台计算机都能同时共享文件服务器和打印机，并访问互联网。
Strong security to prevent unauthorized access to student personal data and exam records.

强大的安全性，以防止未经授权访问学生个人数据和考试记录。
A cost-effective solution using standard hardware and open-source software where possible.

一个具有成本效益的解决方案，尽可能使用标准硬件和开源软件。
A grade calculation program that accepts raw marks, converts them into grades A*–U, and can sort the list by performance.

一个成绩计算程序，接受原始分数，将其转换为A*到U的等级，并能按表现排序列表。

3. Hardware Components | 硬件组件

The lab requires careful hardware selection. Each workstation will be a desktop PC with 8 GB RAM and a solid-state drive for fast booting. The file server needs a larger capacity hard disk (2 TB) and a tape drive for backups. A gigabit network switch will connect all wired devices, and a wireless access point will allow teachers to connect laptops. A dedicated firewall appliance separates the lab network from the school’s main network.

实验室需要仔细选择硬件。每台工作站将是一台配备8 GB内存和固态硬盘的台式机，以实现快速启动。文件服务器需要更大容量的硬盘（2 TB）和一个用于备份的磁带机。一台千兆网络交换机将连接所有有线设备，一个无线接入点将允许教师连接笔记本电脑。一台专用防火墙设备将实验室网络与学校主网络隔离开来。

4. Network Topology Selection | 网络拓扑选择

Choosing the right topology affects performance and reliability. The table below compares common options for this scenario:

选择合适的拓扑结构会影响性能和可靠性。下表比较了该场景的常见选项：

Topology	Advantages	Disadvantages
Star	Easy to install, central management, one cable break does not affect others.	Requires more cable; if central switch fails, whole network down.
Bus	Simple, uses less cable.	Hard to troubleshoot; a break in backbone stops all traffic.
Mesh	Highly redundant, reliable.	Expensive due to many cables; complex setup.

The star topology is recommended because it is the most practical for a single room lab, offering a good balance between cost and reliability. A central 32-port switch will accommodate all devices with room for expansion.

推荐使用星型拓扑，因为它对单个房间的实验室最实用，在成本和可靠性之间取得了良好的平衡。一台中央32端口交换机将容纳所有设备，并留有扩展空间。

5. IP Addressing and Subnetting | IP地址与子网划分

Each device on the network needs a unique IP address. We will use the private IPv4 address range 192.168.10.0/24. The subnet mask 255.255.255.0 allows up to 254 hosts, which is more than enough. The server will have a static IP (192.168.10.10), the printer 192.168.10.20, and workstations will receive dynamic IPs from a DHCP server running on the router. The default gateway is set to 192.168.10.1.

网络上的每个设备都需要唯一的IP地址。我们将使用私有IPv4地址范围192.168.10.0/24。子网掩码255.255.255.0最多允许254台主机，绰绰有余。服务器将拥有静态IP（192.168.10.10），打印机为192.168.10.20，工作站将从路由器上运行的DHCP服务器获取动态IP。默认网关设为192.168.10.1。

Converting these numbers to binary helps understand how subnetting works. For instance, the IP 192.168.10.10 in binary is:

将这些数字转换为二进制有助于理解子网划分的工作原理。例如，IP地址192.168.10.10的二进制表示为：

11000000.10101000.00001010.00001010

6. Data Security Measures | 数据安全措施

Protecting student grades is critical. The following security layers will be implemented:

保护学生成绩至关重要。将实施以下安全层：

User Authentication: Each student and teacher has a unique username and strong password. Passwords must contain at least 8 characters, including digits and symbols, and are hashed using SHA-256 before storage.

用户认证：每位学生和教师都有唯一的用户名和强密码。密码必须至少包含8个字符，包括数字和符号，并在存储前使用SHA-256进行哈希处理。
Encryption: All data transmitted between workstations and the server is encrypted using TLS. Sensitive files on the server are encrypted at rest with AES-128.

加密：工作站与服务器之间传输的所有数据使用TLS加密。服务器上的敏感文件使用AES-128进行静态加密。
Firewall Rules: The firewall blocks all inbound connections except those needed for the grade application and file sharing. Outbound traffic is filtered to prevent malware communication.

防火墙规则：防火墙阻止所有入站连接，除了成绩应用和文件共享所需的连接。过滤出站流量以防止恶意软件通信。

7. Data Representation: Binary and Grades | 数据表示：二进制与等级

Computers store numbers as binary. Exam marks, ranging from 0 to 100, require 7 bits (2⁷ = 128, enough for values 0–127). For example, a mark of 75 is represented as:

计算机将数字存储为二进制。考试分数范围从0到100，需要7位（2⁷ = 128，足够表示0–127的值）。例如，分数75表示为：

1001011

The grade program uses a simple conversion scale. Both binary and decimal marks are mapped to letter grades:

成绩程序使用简单的转换表。二进制和十进制分数都被映射到字母等级：

Mark (Decimal)	Mark (7-bit Binary)	Grade
90–100	1011010 – 1100100	A*
70–89	1000110 – 1011001	A
60–69	0111100 – 1000101	B
50–59	0110010 – 0111011	C
40–49	0101000 – 0110001	D
0–39	0000000 – 0100111	U

8. Algorithm Design: Sorting Scores | 算法设计：排序分数

After grades are computed, the headteacher wants a list sorted from highest to lowest mark. A simple bubble sort algorithm is suitable because the list is small (30 records). The logic in pseudocode:

在计算出等级后，校长希望得到一个从最高分到最低分排序的列表。简单的冒泡排序算法很合适，因为列表很小（30条记录）。伪代码逻辑如下：

REPEAT n-1 TIMES
FOR i = 0 TO n-2
IF marks[i] < marks[i+1] THEN
SWAP marks[i] AND marks[i+1]
END FOR
END REPEAT

This descending order sort can also be implemented in Python. The time complexity is O(n²), acceptable for a single class. To improve efficiency, a merge sort could be used for larger datasets, but for 30 items bubble sort is simple to code and sufficient.

这种降序排序也可以用Python实现。时间复杂度为O(n²)，对于单个班级是可以接受的。为了提升效率，大数据集可以使用归并排序，但对于30个项目，冒泡排序编写简单且足够。

9. Ethics and Data Privacy | 伦理与数据隐私

Handling student data comes with legal and ethical responsibilities under the UK General Data Protection Regulation (GDPR). The school must:

处理学生数据涉及英国《通用数据保护条例》(GDPR)下的法律和伦理责任。学校必须：

Obtain consent from parents or carers for storing and processing grades digitally.

获得家长或监护人的同意，以数字方式存储和处理成绩。
Collect only the minimum data needed (exam marks and IDs, not full names or addresses).

只收集最少所需数据（考试分数和学号，而不是全名或地址）。
Allow students to access their own records and correct any errors.

允许学生访问自己的记录并更正任何错误。
Ensure data is deleted when no longer required, usually after the student leaves the school.

确保在不再需要时删除数据，通常是在学生离开学校后。

10. Testing and Evaluation | 测试与评估

Before deployment, the system is tested rigorously. A test plan includes:

在部署之前，系统要经过严格测试。测试计划包括：

Network Test: Check connectivity between all devices; verify internet access and shared printer functionality. Simulate a switch failure to ensure alerts work.

网络测试：检查所有设备之间的连接；验证互联网访问和共享打印机功能。模拟交换机故障以确保警报正常工作。
Security Test: Attempt unauthenticated access to the server; run a password strength checker; scan for open ports.

安全测试：尝试未经认证访问服务器；运行密码强度检查器；扫描开放端口。
Program Test: Input boundary marks (0, 100, 50, 39, 40) and check grade output; confirm sorting order with a known dataset.

程序测试：输入边界分数（0, 100, 50, 39, 40）并检查等级输出；用已知数据集确认排序顺序。

Evaluation shows that the star topology performs well with zero down-time during normal use, and the bubble sort program produces accurate results. The security audit highlights the need for regular password resets and firewall updates.

评估表明，星型拓扑在正常使用期间零停机，表现良好，冒泡排序程序生成准确结果。安全审计强调需要定期重置密码和更新防火墙。

11. Recommendations and Conclusion | 建议与结论

The proposed solution meets all user requirements within budget. Key recommendations:

拟议的解决方案在预算内满足了所有用户需求。主要建议：

Adopt a managed 32-port gigabit switch with Power over Ethernet (PoE) to support future wireless access points.

采用带有以太网供电(PoE)的托管32端口千兆交换机，以支持未来的无线接入点。
Use open-source firewall (pfSense) and file server (FreeNAS) to reduce licensing costs.

使用开源防火墙(pfSense)和文件服务器(FreeNAS)来降低许可成本。
Train staff on data protection principles and the grade program.

对员工进行数据保护原则和成绩程序的培训。

In conclusion, this case study demonstrates how computing concepts like networks, binary, and algorithms solve real-world problems. The school now has a secure, efficient system ready for the digital age.

总之，本案例研究展示了网络、二进制和算法等计算机概念如何解决实际问题。学校现在拥有了一个安全、高效的系统，为数字时代做好了准备。

12. Reflection | 反思

This exercise reinforces the importance of linking theoretical knowledge to practice. You have seen how a star network provides centralized control, how binary basics underpin data storage, and how an algorithm can be chosen based on data size. Remember that in any IT project, security and ethics are not afterthoughts but core design requirements.

这个练习强化了将理论知识联系实践的重要性。你已经看到星型网络如何提供集中控制，二进制基础如何支撑数据存储，以及如何根据数据大小选择算法。请记住，在任何IT项目中，安全与伦理不是事后思考，而是核心设计要求。

Published by TutorHao | Computer Science Revision Series | aleveler.com

更多咨询请联系16621398022（同微信）

Case Study Practical Workout | 案例分析实战演练