Estudo de caso
International Baccalaureate · IB Diploma · Computer Science · SL Tópico 8 4:21 Narração em inglês · Legendas em inglês + 中文 gravadas
Capítulos
Transcrição
Each year the IB publishes a case study some months before the examinations, and some questions are based on it.
每年 IB 会在考试前几个月发布一份案例研究，部分考题就以它为基础。
Your teacher will give you the current case.
老师会把当年的案例发给你。
This lesson teaches the method, using a short fictional case written for practice.
本课用一个为练习而写的简短虚构案例，教你准备和作答的方法。
A case study is a few pages about one real use of computing, such as a hospital or a farm.
案例研究是几页关于计算机一项真实应用的材料，比如一家医院或一个农场。
It describes the organisation and its problem, the technology, the stakeholders, the challenges, and a list of additional terms you are expected to research.
它描述组织及其问题、所用技术、利益相关者、面临的挑战，以及一份需要你自行查阅的补充术语表。
Questions test whether you can apply your knowledge to that scenario.
考题检验你能否把知识应用到这个情境中。
You have months, so work in stages. Read the case twice and mark every technical term. Build a glossary. Map each part of the case to the course themes. Tabulate the stakeholders. Research each challenge. Then write practice answers and check every claim against the case.
你有好几个月，所以要分阶段准备：把案例读两遍并标出每个技术术语；建立术语表；把案例的每一部分对应到课程主题；列出利益相关者表；研究每个挑战；最后写练习答案，并对照案例逐条核对。
The glossary step is the one most students rush.
建术语表这一步是多数学生最容易草草带过的。
Edge computing means processing data near where it is collected: that is a definition.
“边缘计算是在数据采集地附近处理数据”只是定义。
Add that each locker checks codes itself, so it works when the mobile link is down, and it becomes case knowledge.
加上“每个储物柜自己核验二维码，所以 4G 断开时也能工作”，它就变成了案例知识。
Here is the practice case, which is fictional.
这是练习用的虚构案例。
A library with eight branches puts smart lockers outside each one.
一家有八个分馆的图书馆在每个分馆外安装智能储物柜。
A member reserves a book in the app and gets a QR code; at the locker, the scan opens one door.
会员在应用里预约图书，拿到一个二维码；在柜前扫码，一扇柜门就会打开。
Each locker talks to the cloud server over 4G.
每个储物柜通过 4G 与云服务器通信。
The server holds the database and a model that predicts demand.
服务器保存数据库和一个预测需求的模型。
The library names four challenges. Lockers must keep working when the 4G connection fails. Reading history is personal data, but it would improve predictions. The model must not give poorer service to branches in poorer areas. And a QR code must work only for the member it was issued to.
图书馆列出了四个挑战：4G 断开时储物柜必须照常工作；借阅历史是个人数据，但能改进预测；模型不能让较贫困地区的分馆得到较差的服务；二维码只能被它发给的那位会员使用。
Members want easy, private collection at any hour, which pulls against better predictions.
会员希望随时方便、私密地取书，这与更好的预测相冲突。
Staff want fewer wasted trips, but filling lockers is new work.
员工希望少跑冤枉路，但装柜是新增的工作。
Managers want more loans at a fair cost.
管理层希望以合理成本增加借阅量。
The council wants a fair service in every area, so prediction bias matters to it.
市议会希望各区服务公平，所以预测偏差对它很重要。
Now map the case to the course. The locker and its scanner are computer fundamentals. The 4G link and the server are networks. Members, books and loans are a database. Demand prediction is machine learning. QR codes bring in validation and hashing.
现在把案例对应到课程：储物柜和扫码器属于计算机基础；4G 链路和服务器属于网络；会员、图书和借阅构成数据库；需求预测是机器学习；二维码涉及验证和哈希。
Every question starts with a command term. Outline wants a brief account. Describe wants the features in order. Explain needs reasons: point, because, so. Discuss and evaluate need both sides and then a conclusion or judgement with a reason.
每道题都以指令词开头。 outline 要简要说明；describe 按顺序写出特征；explain 需要理由：观点、因为、所以；discuss 和 evaluate 要写出两方面，再给出带理由的结论或判断。
Explain why each locker should store valid codes locally.
解释为什么每个储物柜要在本地保存有效码。
Point: if the link fails, the locker cannot ask the server.
观点：链路断开时，柜子无法询问服务器。
Because: coverage drops, and challenge one says lockers must keep working.
因为：信号会中断，而挑战一要求柜子照常工作。
So: with a local list it checks the code itself.
所以：有了本地列表，它能自己核验。
Link: when the link returns, it sends its log and the loan records catch up.
联系：链路恢复后，它上传开柜记录，借阅记录随之更新。
Should the library use reading histories?
图书馆该用借阅历史吗？
For: predictions improve, so members wait less.
支持：预测更准，会员等待更少。
Against: the data is personal, and a breach would harm members.
反对：数据涉及个人隐私，一旦泄露会伤害会员。
A middle way: the model needs branch totals, not individuals, so use anonymised branch-level counts.
折中办法：模型需要的是分馆总数而不是个人数据，所以只用匿名的分馆级统计。
That conclusion, with its reason, earns the top marks.
带着理由的这个结论才能拿高分。
The commonest weakness is a generic answer.
最常见的毛病是空泛的答案。
Encryption keeps data safe could be written about any system.
“加密保护数据安全”放在任何系统上都成立。
Say what is encrypted in the case and from whom.
要说清案例中加密的是什么、防的是谁。
Give both sides before you judge, and never add facts the case does not state.
下判断前先写出两方面，也不要添加案例没有给出的事实。
Try these. Name two stakeholders and their wants. Say why a QR code should change for each reservation. Explain how training on busy branches could be unfair. Then discuss a library card instead of a code.
试试这些：说出两个利益相关者及其诉求；说明为什么每次预约的二维码都要不同；解释只用繁忙分馆的数据训练为什么可能不公平；再讨论用借书证代替二维码。
In the exam, name something from the case in every answer: a stakeholder, a device or a challenge.
考试时每个答案都要提到案例中的具体内容：一个利益相关者、一个设备或一个挑战。
Read the command term first.
先看指令词。
Use the course terms the examiner expects, and never add facts the case does not state.
使用考官期待的课程术语，并且不要添加案例没有给出的事实。