📚 Case Study Practice for Year 7 AQA Science | AQA七年级科学案例分析实战演练
Case studies are a vital part of Year 7 AQA Science. They test your ability to think like a scientist—planning investigations, analysing data, and drawing evidence-based conclusions. This article provides a step-by-step guide to tackling case study questions, complete with a real-life example and exam-style practice. By the end, you will feel confident in approaching any scenario the exam throws at you.
案例分析是AQA七年级科学的重要组成部分。它们考查你是否能像科学家一样思考——规划探究、分析数据并得出基于证据的结论。本文将逐步指导你攻克案例分析题，并提供一个真实案例和考试式练习。读完本文，你将有信心应对考试中出现的任何情境。
1. What is a Case Study in Science? | 什么是科学案例分析？
In KS3 Science, a case study describes a scientific investigation. You are given a scenario, often with a hypothesis, a method, a table of results, and sometimes a graph. Your job is to interpret the information, identify variables, spot patterns, draw conclusions, and evaluate the reliability of the experiment.
在KS3科学中，案例分析描述一次科学探究。你会得到一个情境，通常包括假设、方法、结果表格，有时还有图表。你的任务是解读信息、识别变量、发现规律、得出结论并评价实验的可靠性。
Case studies mimic real research. They show that science is not just learning facts but applying them to solve problems. The AQA exam often includes a short case study followed by several questions worth around 4–6 marks. Mastering these can significantly boost your grade.
案例分析模拟真实研究。它表明科学不仅是学习事实，更是运用事实解决问题。AQA考试常包含一个简短的案例分析，后跟几道约4–6分的题目。掌握它们能显著提高你的成绩。
2. Getting to Know the Scenario | 了解情境
Start by reading the description carefully. Underline key information: the aim of the investigation, what is being changed (independent variable), what is being measured (dependent variable), and what must be kept the same (control variables). Also note any apparatus or special conditions mentioned.
首先仔细阅读描述。在关键信息下划线：探究目的、改变了什么（自变量）、测量了什么（因变量）以及必须保持不变的量（控制变量）。还要注意提到的任何仪器或特殊条件。
For example, a case study might say: 'Tom wanted to find out if the temperature of water affects how quickly sugar dissolves. He used 100 ml of water each time and stirred for 30 seconds.' Here, the independent variable is water temperature, the dependent variable is dissolving time, and controls include the volume of water and stirring time.
例如，案例可能写道：“汤姆想知道水温是否影响糖溶解的速度。他每次使用100毫升水，搅拌30秒。”这里自变量是水温，因变量是溶解时间，控制变量包括水的体积和搅拌时间。
3. Identifying Variables | 识别变量
Variables are the foundation of any experiment. The independent variable is what you change deliberately. The dependent variable is what you measure. Control variables are factors that could affect the outcome and must be kept constant to make the test fair.
变量是任何实验的基础。自变量是你有意改变的。因变量是你测量的。控制变量是可能影响结果且必须保持不变以确保公平测试的因素。
In the exam, you may be asked: 'What is the independent variable in this investigation?' or 'Give two control variables.' Always refer back to the text. Write them clearly. A common mistake is confusing the independent and dependent variables—remember, the dependent variable depends on what you changed.
考试中可能会问：“本探究中的自变量是什么？”或“给出两个控制变量”。始终回看文本。清晰地写下来。一个常见错误是混淆自变量和因变量——记住，因变量取决于你改变的量。
4. Making Predictions | 做出预测
Before seeing results, scientists make a prediction based on a hypothesis. A good prediction uses scientific reasoning and suggests a trend. It is often written as: 'If ... then ... because ...' For example, 'If the water temperature increases, then the sugar will dissolve faster because particles have more energy and move faster.'
在看到结果之前，科学家会根据假设做出预测。一个好的预测使用科学推理并提出一种趋势。通常写作：“如果……那么……因为……”例如，“如果水温升高，那么糖溶解得更快，因为粒子能量更高，运动更快。”
In a case study task, you might need to state the prediction that matches the given hypothesis, or explain why a prediction makes sense using particle theory or everyday experience. Even if no prediction is given, practise forming one: this sharpens your analysis later.
在案例分析任务中，你可能需要陈述与给定假设相匹配的预测，或使用粒子理论或日常经验解释预测的合理性。即使没有给出预测，也要练习形成一个：这能磨炼你后续的分析能力。
5. Collecting and Recording Data | 收集与记录数据
Reliable data is collected through careful measurement and repeated trials. In most Year 7 case studies, you will see a results table. Learn to read it properly: check units, headings, and whether there are anomalies (results that do not fit the pattern).
可靠的数据通过仔细测量和重复试验收集。在大多数七年级案例分析中，你会看到结果表格。学会正确阅读：检查单位、标题，以及是否有异常值（不符合规律的结果）。
For instance, a table might show temperature in degrees Celsius (°C) and dissolving time in seconds (s). If one reading is very different from the others at the same temperature, it is probably an anomaly. You might be asked to circle it and suggest a reason, such as a misreading of the stopwatch.
例如，一个表格可能显示温度以摄氏度（°C）为单位，溶解时间以秒（s）为单位。如果同一温度下的某个读数与其他值差异很大，那很可能是一个异常值。你可能需要圈出它并说明原因，例如看错秒表。
6. Drawing Tables and Graphs | 绘制表格和图表
Sometimes the case study provides incomplete data and asks you to finish a table or draw a bar chart or line graph. Remember: the independent variable goes on the x-axis (horizontal), and the dependent variable on the y-axis (vertical). Label axes with units, choose even scales, and plot points accurately.
有时案例分析会提供不完整的数据，要求你补全表格或绘制条形图或折线图。记住：自变量放在x轴（横轴），因变量放在y轴（纵轴）。为坐标轴标注单位，选择均匀的刻度，并精确描点。
A line graph is best when the independent variable is continuous (e.g., temperature), while a bar chart suits categories (e.g., type of material). If you are asked to draw a graph, use a ruler, draw a 'line of best fit' (not dot-to-dot) for line graphs, and add a title.
当自变量是连续量（如温度）时，折线图最合适；而条形图适合类别（如材料类型）。如果要求你画图，用尺子、画“最佳拟合线”（而非逐点连线）用于折线图，并添加标题。
7. Analysing Results | 分析结果
Analysis means looking for patterns. Ask yourself: As the independent variable increases, does the dependent variable increase, decrease, or stay the same? Is the relationship linear or non-linear? Use data directly—quote numbers—to support your statements.
分析意味着寻找规律。问自己：随着自变量增大，因变量是增大、减小还是保持不变？关系是线性的还是非线性的？直接用数据——引用数字——来支持你的陈述。
For example, 'When the temperature was 20°C, dissolving took 45 seconds. At 60°C, it took only 12 seconds. This shows that higher temperature decreases dissolving time.' This level of detail earns full marks. Avoid vague phrases like 'it got better'.
例如，“当温度为20°C时，溶解需要45秒。在60°C时仅需12秒。这表明较高温度缩短了溶解时间。”这种详细程度能获得满分。避免含糊不清的说法，如“结果变好了”。
8. Drawing Conclusions | 得出结论
A conclusion must directly answer the original question or aim. It summarises the trend and is supported by data. Write: 'The results show that ...' or 'Overall, ...' Then state whether the prediction was correct, and give a brief scientific explanation.
结论必须直接回答最初的问题或目的。它总结趋势并有数据支持。写作：“结果显示……”或“总体而言，……”然后说明预测是否正确，并给出简要的科学解释。
Using particle theory: 'As water temperature rose, sugar particles and water particles collided more often and with more energy, so the sugar dissolved faster.' Always link back to key scientific ideas.
使用粒子理论：“随着水温升高，糖粒子和水粒子碰撞更频繁、能量更高，因此糖溶解得更快。”始终与关键科学概念联系起来。
9. Evaluating the Investigation | 评价探究
Evaluation goes beyond the conclusion. You must judge how trustworthy the data is. Consider: Was the method fair? Were there enough repeats? Were all control variables managed? Did anomalies appear? How could the experiment be improved?
评价超越结论。你必须判断数据的可信度。考虑：方法是否公平？有足够的重复吗？所有控制变量都得到了管理吗？出现了异常值吗？实验可以如何改进？
Common improvements include: using more precise equipment (e.g., digital thermometer instead of liquid-in-glass), doing more trials to calculate an average, controlling light or draughts, or making measurements at more values of the independent variable. Explain why the change would increase reliability or accuracy.
常见的改进包括：使用更精确的设备（如数字温度计代替液体温度计），进行更多试验以计算平均值，控制光线或气流，或在更多自变量取值下进行测量。解释为什么该改变会提高可靠性或准确性。
10. Real-Life Example: Plant Growth Experiment | 真实案例：植物生长实验
Let's apply these skills. Read the following case study:
让我们运用这些技能。阅读以下案例分析：
Scenario: Maria wanted to see how different amounts of light affect the growth of cress seedlings. She placed three pots of 10 seeds on a windowsill. Pot A received full daylight. Pot B was covered with one sheet of tracing paper. Pot C was placed in a cardboard box with no light. She watered each pot with 10 ml of water every day. After 7 days, she measured the height of the tallest seedling in each pot.
情境：玛丽亚想了解不同光照量如何影响水芹幼苗的生长。她将三盆各含10颗种子的盆放在窗台上。花盆A接受充足的日光。花盆B用一张描图纸覆盖。花盆C放在不透光的纸板箱中。她每天给每盆浇10毫升水。7天后，她测量每盆中最高的幼苗的高度。
| Pot | 花盆 | Condition | 条件 | Seedling height (cm) | 幼苗高度（厘米） |
|---|---|---|
| A | Full light | 充足光照 | 5.2 |
| B | Dim light (tracing paper) | 弱光（描图纸） | 3.8 |
| C | No light | 无光 | 1.5 |
Now answer the following as practice:
现在作为练习，回答以下问题：
- Q1. What is the independent variable? | 问题1. 自变量是什么？
- Q2. State two control variables. | 问题2. 陈述两个控制变量。
- Q3. Describe the trend shown by the results. | 问题3. 描述结果所示的趋势。
- Q4. Suggest why seeds in Pot C still grew (to 1.5 cm) even without light. | 问题4. 解释为什么花盆C中的种子在无光条件下仍然生长（至1.5厘米）。
- Q5. Evaluate the method and propose one improvement. | 问题5. 评价该方法并提出一项改进。
Answers: Q1: Amount of light (or light condition). Q2: Any two from: volume of water (10 ml), type of seed, number of seeds per pot, type of soil, location (windowsill), watering frequency. Q3: As light decreased, seedling height decreased. Pot A had the tallest (5.2 cm), Pot C the shortest (1.5 cm). Q4: Seeds contain stored food (cotyledons) that provided energy for initial growth until food ran out. Without light, they grew tall and spindly, but growth was limited. Q5: The method used only one measurement (the tallest seedling), which could be unreliable. Improvement: measure all seedlings and calculate a mean height for each pot, or repeat the whole experiment. This would reduce the effect of any unusually strong or weak seedling.
答案：问题1：光照量（或光照条件）。问题2：以下任选两个：水量（10毫升）、种子种类、每盆种子数、土壤类型、放置位置（窗台）、浇水频率。问题3：随着光照减少，幼苗高度降低。花盆A最高（5.2厘米），花盆C最矮（1.5厘米）。问题4：种子含有储存的食物（子叶），为初始生长提供能量，直到食物耗尽。没有光，它们会长得细长，但生长有限。问题5：该方法仅测量了最高的幼苗，可能不可靠。改进：测量所有幼苗并计算每盆的平均高度，或重复整个实验。这将减少任何异常强壮或瘦弱幼苗的影响。
11. Practice Questions without a Prompt | 无提示练习题
Here is another short scenario to try on your own. Write your answers on paper before checking the suggested responses below.
这是另一个简短的场景，可自行尝试。在下文查看建议答案前，先在纸上写下你的答案。
Scenario: James investigated how the length of a pendulum string affects the time it takes to swing 10 times. He used a 10 g mass, released from the same angle each time. His results:
情境：詹姆斯探究了单摆的绳子长度如何影响其摆动10次所需的时间。他使用一个10克的砝码，每次从相同角度释放。他的结果：
| String length (cm) | 绳长（厘米） | Time for 10 swings (s) | 摆动10次的时间（秒） |
|---|---|
| 20 | 9.1 |
| 40 | 12.8 |
| 60 | 15.6 |
| 80 | 18.2 |
| 100 | 20.5 |
- Q1: Identify the independent and dependent variables. | 问题1：指出自变量和因变量。
- Q2: Name one control variable. | 问题2：说出一个控制变量。
- Q3: Plot a line graph of the data. | 问题3：绘制数据的折线图。
- Q4: Describe the relationship between string length and swing time. | 问题4：描述绳长与摆动时间之间的关系。
- Q5: Predict the time for 10 swings for a 50 cm string. | 问题5：预测绳长为50厘米时摆动10次所需的时间。
Suggested answers: 10 g), release angle, number of swings measured (10), or same pendulum bob. Q3: (Graph should have string length on x-axis, time on y-axis, labelled axes, points correctly plotted, line of best fit). Q4: As string length increases, the time for 10 swings also increases. The relationship is non-linear; the time increases more slowly at longer lengths? e of 20 cm added 3.7, 2.8, 2.6, 2.3 s. It is a curve levelling off slightly. You could say 'the time increases at a decreasing rate' cm (15.6 s). Using interpolation, approximately 14.2 s (exact value may vary, accept 14.0 – 14.5 s).
建议答案：问题1：自变量=绳长；因变量=摆动10次的时间。问题2：砝码质量（10克）、释放角度、测量的摆动次数（10次）或同一个摆锤。问题3：（图中x轴为绳长，y轴为时间，坐标轴标注完整，点描画正确，绘有最佳拟合线）。问题4：绳长增加时，摆动10次的时间也增加。关系是非线性的；在较长的绳长下，时间增长速度减慢。可以说“时间以递减的速率增加”。问题5：50厘米绳长介于40厘米（12.8秒）和60厘米（15.6秒）之间。通过插值法，约为14.2秒（精确值可能不同，接受14.0–14.5秒）。
12. Tips for Exam Success | 考试成功技巧
Read the question twice. Many marks are lost by misreading what is being asked. Highlight command words like 'describe', 'explain', 'suggest'. 'Describe' means say what happens; 'explain' means say why using science.
读题两遍。很多分数都是因为误读题目要求而丢掉的。高亮指令词如“描述”“解释”“建议”。“描述”意思是说出发生了什么；“解释”意思是运用科学说出为什么。
Use data. Always quote numbers when describing trends. For example, 'from 20 cm to 100 cm, the swing time increased from 9.1 s to 20.5 s.' This proves you can extract information.
使用数据。描述趋势时始终引用数字。例如，“从20厘米到100厘米，摆动时间从9.1秒增加到20.5秒。”这证明你能提取信息。
Write in full sentences. One-word answers rarely get full marks in case study questions. Show your reasoning.
写完整的句子。在案例分析题中，一个词的答案很少得满分。展示你的推理过程。
Check units and scales. If you draw a graph, check that the scale goes up evenly and covers the range of data. Label axes with quantities and units.
检查单位和刻度。绘制图表时，检查刻度是否均匀增加并覆盖数据范围。用数量和单位标注坐标轴。
Practise with unfamiliar scenarios. The exam will present new situations. The skills are identical. The more you practise identifying variables, spotting patterns, and evaluating methods, the quicker you become.
用不熟悉的情境练习。考试会给出新情境。技能是相同的。你越多练习识别变量、发现规律和评价方法，就会越快上手。
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