📚 Year 10 CCEA Science: Case Study Practical Exercises | 科学：案例分析实战演练
In Year 10 CCEA Science, a case study is not just about memorising facts — it is a practical investigation that requires you to plan, carry out, analyse and reflect on a scientific enquiry. This revision guide will walk you through every step, with clear textual examples and real-world questions to sharpen your skills.
在 CCEA 十年级科学课程中，案例分析不只是死记硬背——它是一项实践探究，要求你规划、实施、分析并反思一个科学调查。这本复习指南将带你走完每一步，配以清晰的文字示例和真实情境问题，帮你提升技能。
1. What Is a Case Study? | 什么是案例分析？
A case study in CCEA Science is an in-depth investigation of a scientific question. It often includes a planning stage, a practical experiment, collection of data, analysis of results and an evaluation of the whole process. The task is designed to test your ability to think like a scientist.
CCEA 科学中的案例分析是对一个科学问题的深入调查。它通常包括计划阶段、动手实验、数据收集、结果分析和对整个过程的评估。这项任务旨在考察你是否能像科学家一样思考。
The investigation might be based on biology (e.g. enzyme activity), chemistry (e.g. rate of reaction) or physics (e.g. resistance of a wire). You are expected to show understanding of scientific method, not just recall facts.
调查可能基于生物学（如酶活性）、化学（如反应速率）或物理学（如导线电阻）。你需要展现对科学方法的理解，而不仅仅是回忆事实。
2. Understanding the Task | 理解题目要求
Read the case study brief carefully. It will state the aim, and sometimes provide background information. Your job is to turn that brief into a testable hypothesis and a fair experiment. Do not rush — highlight keywords and write down what you already know about the topic.
仔细阅读案例分析简介。它会说明目的，有时还会提供背景信息。你的任务是将简介转化为可检验的假设和一个公平实验。不要着急——标出关键词，并写下你对此主题已有的知识。
For example, a brief might say: 'Investigate how temperature affects the time for a sugar cube to dissolve in water.' Immediately you can see the independent and dependent variables. The question is already prompting you to think about control variables, such as volume of water and stirring speed.
例如，一个简介可能写道：“研究温度如何影响方糖在水中溶解的时间。” 你立刻就能看出自变量和因变量。问题已经在引导你思考控制变量，比如水的体积和搅拌速度。
3. Forming a Scientific Hypothesis | 形成科学假设
A hypothesis is a prediction with a scientific reason. Use the format: 'If ... then ... because ...' For instance: 'If the temperature of the water is increased, then the sugar cube will dissolve faster because the water molecules have more kinetic energy and collide with the sugar more frequently.'
假设是一种带有科学理由的预测。使用“如果……那么……因为……”的格式。例如：“如果水温升高，那么方糖会溶解得更快，因为水分子具有更大的动能，与糖碰撞更频繁。”
Your hypothesis must be based on scientific knowledge, not just a guess. In CCEA case studies, you will be marked on how well your explanation links cause and effect.
你的假设必须基于科学知识，而不仅仅是猜测。在 CCEA 案例分析中，评分会根据你对因果关系的解释有多好。
4. Identifying Variables | 识别变量
There are three types of variables: independent (what you change), dependent (what you measure) and control (what you keep the same). For the sugar cube example: independent variable is temperature; dependent variable is time to dissolve; control variables include volume of water, size of sugar cube, type of sugar and whether you stir.
变量有三种类型：自变量（你改变的量）、因变量（你测量的量）和控制变量（你保持不变的量）。以方糖例子为例：自变量是温度；因变量是溶解时间；控制变量包括水的体积、方糖的大小、糖的种类以及是否搅拌。
A common mistake is not listing enough control variables. Think carefully about what could affect the results. For a biology case study on plant growth, control variables might be light intensity, amount of water, type of soil and pot size.
一个常见错误是列出的控制变量不够。仔细思考什么会影响结果。以植物生长的生物学案例分析为例，控制变量可能包括光照强度、浇水量、土壤类型和花盆大小。
5. Designing the Method | 设计实验方法
Your method should be written as a step-by-step list in bullet points or numbered steps. Use clear, instructional language: 'Measure 50 cm³ of water using a measuring cylinder and pour it into a beaker.' Avoid using 'I' or 'we'. Include precise quantities and how to use apparatus correctly.
你的方法应该写成一步一步的列表，用项目符号或编号。使用清晰的指示性语言：“用量筒量取 50 立方厘米水，倒入烧杯中。” 避免使用“我”或“我们”。包括精确的数值以及如何正确使用仪器。
Each step must be specific enough that another student could replicate your experiment exactly. Mention the range of the independent variable and the number of repeats for each value. For reliability, you usually need at least three repeats.
每个步骤都要足够具体，让另一名学生可以完全复制你的实验。说明自变量的取值范围以及每个数值的重复次数。为了可靠性，通常至少需要三次重复。
6. Risk Assessment and Ethics | 安全评估与伦理
Always include a risk assessment. Identify hazards, the associated risk, and how to minimise it. For example, using hot water: risk of scalding, so handle with tongs and wear safety goggles. Keep it simple and relevant.
始终包含安全评估。识别危险源、相关风险以及如何降低风险。例如，使用热水：有烫伤风险，因此用钳子操作并佩戴护目镜。保持简单和有关联性。
In biology case studies involving living organisms, you must also consider ethical issues. For instance, when using pondweed or yeast, you should minimise harm and return organisms to their natural habitat after the experiment if possible. Mention these points to gain top marks.
在涉及活体生物的生物学案例分析中，你还必须考虑伦理问题。例如，使用水草或酵母时，应将伤害降到最低，并在实验后尽可能将生物放回自然栖息地。提到这些点以获取高分。
7. Data Collection and Recording | 数据收集与记录
Record all raw data in a well-organised results table before you draw any graph. The independent variable goes in the first column; the dependent variable in subsequent columns. Include units in the headings, not just in the cells.
在绘制任何图表之前，将所有原始数据记录在一个组织良好的结果表中。自变量放在第一列；因变量放在后续列。单位要写在表头中，而不是仅写在单元格内。
For example: | Temperature (°C) | Time to dissolve (s) Trial 1 | Trial 2 | Trial 3 | Mean | Then calculate the mean (average) for each temperature and record it. Anomalous results should be identified but not removed without a valid reason.
例如：| 温度 (°C) | 溶解时间 (秒) 试验1 | 试验2 | 试验3 | 平均值 | 然后计算每个温度的平均值并记录。异常结果应该被识别出来，但除非有正当理由，否则不应删除。
8. Presenting Data: Tables and Graphs | 数据展示：表格与图表
CCEA expects you to plot a line graph or sometimes a bar chart, depending on the type of data. For continuous independent variables like temperature, a line graph is appropriate. Use a sharp pencil, label axes with quantity and unit, choose appropriate scales and plot points with small crosses.
CCEA 希望你绘制线图或有时是条形图，具体取决于数据类型。对于像温度这样的连续自变量，线图是合适的。使用尖铅笔，用物理量和单位标记坐标轴，选择合适的刻度，并用小十字标出数据点。
Do not connect the dots from the origin unless there is a physical reason. Draw a smooth line of best fit — it could be a curve or a straight line depending on the trend. If the relationship is directly proportional, the line should go through the origin.
除非有物理原因，否则不要从原点连接各点。画一条平滑的最佳拟合线——根据趋势，它可以是曲线或直线。如果关系是正比关系，线应该经过原点。
9. Analysis and Conclusion | 分析与结论
Describe what the graph shows: the pattern or trend. For example: 'As temperature increases from 20°C to 60°C, the time to dissolve decreases. The decrease is not linear; the rate of decrease lessens at higher temperatures.' Refer to data points, such as 'the time dropped from 85 s to 25 s.'
描述图表显示的内容：模式或趋势。例如：“随着温度从 20°C 升高到 60°C ，溶解时间减少。下降并非线性；在较高温度时下降速率减小。”引用数据点，如“时间从 85 秒降至 25 秒。”
Then write a conclusion that links back to the hypothesis. State whether the results support the hypothesis and explain using scientific principles. For the sugar cube case: 'The results support the hypothesis because increased temperature gave molecules more kinetic energy, increasing the frequency and energy of collisions with the sugar surface.'
然后写一个结论，与假设相关联。说明结果是否支持假设，并用科学原理解释。对于方糖案例：“结果支持假设，因为温度升高赋予分子更大动能，增加了与糖表面碰撞的频率和能量。”
10. Evaluation and Improvement | 评估与改进
No experiment is perfect. Identify at least two sources of error or limitations. These could be systematic errors (e.g. a thermometer that is not calibrated) or random errors (e.g. reaction time when using a stopwatch). Explain how each affected the results.
没有完美的实验。至少找出两个误差源或局限性。这可能是系统误差（如温度计未校准）或随机误差（如使用秒表时的反应时间）。解释每个误差如何影响结果。
Suggest realistic improvements. If timing was done by eye, you could suggest using a light gate or video recording to measure more accurately. Add a step or change in apparatus. Always say how the improvement would increase accuracy, reliability or validity.
提出切实可行的改进建议。如果计时是肉眼完成，你可以建议使用光门或录像来更精确地测量。增加步骤或更换仪器。始终说明改进如何提高准确性、可靠性或有效性。
11. Practical Exercise Example | 实战练习示例
Let's apply these skills to a sample case study: 'Investigate the effect of light intensity on the rate of photosynthesis in pondweed, measured by counting oxygen bubbles per minute.' Your task: plan the investigation, identify variables, write a risk assessment, and outline how you would present data.
让我们把这些技能应用到一个样本案例分析中：“研究光照强度对水草光合作用速率的影响，通过每分钟数氧气泡来测量。”你的任务：计划该调查，识别变量，写出安全评估，并概述你将如何展示数据。
Hypothesis: If light intensity increases, then the rate of photosynthesis will increase because more light energy is available for the light-dependent reactions, producing more oxygen.
假设：如果光照强度增加，那么光合作用速率就会增加，因为有更多的光能可用于光反应，产生更多氧气。
Independent variable: light intensity (vary by changing distance of lamp). Dependent variable: number of oxygen bubbles per minute. Control variables: type of pondweed, amount of water, temperature, concentration of CO₂ (add sodium hydrogencarbonate). Method steps: fill a beaker with water, place pondweed, set lamp at 10 cm, count bubbles for 1 minute, repeat 3 times, then move lamp to 20 cm, etc. Risk: electricity near water — keep lamp clamped securely and away from splashes; heat from lamp could raise temperature — place a glass screen in between as a heat filter.
自变量：光照强度（通过改变灯的距离来变化）。因变量：每分钟氧气泡数。控制变量：水草种类、水量、温度、CO₂ 浓度（加入碳酸氢钠）。方法步骤：烧杯装满水，放入水草，将灯置于 10 厘米处，数泡泡 1 分钟，重复 3 次，然后将灯移至 20 厘米处，以此类推。风险：水电相邻——将灯安全夹住并远离溅水；灯的热量会升高温度——在中间放置一块玻璃隔板作为隔热滤光片。
Data table: Distance (cm), Light intensity (arbitrary units, perhaps 1/d²), Bubbles per min Trial 1, 2, 3, Mean. Then graph light intensity on x-axis against mean rate on y-axis. This exercise mirrors what CCEA examiners want.
数据表：距离 (厘米)，光照强度 (任意单位，或许是 1/d²)，每分钟气泡数试验1、2、3，平均值。然后以光照强度为 x 轴，平均速率为 y 轴作图。这个练习反映了 CCEA 考官想要的东西。
12. Common Mistakes and How to Avoid Them | 常见错误与如何避免
One common mistake is writing a method that lacks detail, such as 'add sugar to water'. Always say how much, what temperature, what apparatus. Another is forgetting to include units or using inconsistent scales on graphs. Practise drawing graphs on graph paper beforehand.
一个常见错误是实验方法缺乏细节，比如“往水里加糖”。始终要说多少量、什么温度、什么仪器。另一个错误是忘记包含单位或在图表上使用不一致的刻度。事先在方格纸上练习绘图。
Students often write conclusions that do not refer back to the hypothesis or data. Always use the phrase 'the results show that ...' and quote specific values. In evaluation, avoid saying 'do the experiment more carefully' — give a concrete improvement.
学生经常写出没有回扣假设或数据的结论。始终使用“结果显示……”的短语，并引用具体数值。在评估中，避免说“更仔细地做实验”——要给出具体的改进。
Finally, manage your time. In a CCEA case study task, allocate time for planning, practical work, graphing and writing up. Practise whole investigations under timed conditions so you are not caught off guard.
最后，管理好你的时间。在 CCEA 案例分析任务中，为计划、动手操作、绘图和撰写分配时间。在限时条件下练习完整的调查，这样就不会措手不及。
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