📚 Year 8 SQA Science: Case Study Analysis Practice | 八年级 SQA 科学：案例分析实战演练
Welcome to a hands-on revision guide where we sharpen your scientific investigation skills by working through real-world case studies. This article is designed for Year 8 students following the SQA science curriculum. You will learn how to interpret data, identify variables, draw conclusions, and apply your knowledge—all essential for tackling case study questions confidently.
欢迎来到这份实践复习指南，我们将通过真实案例研究来锻炼你的科学探究能力。本文专为修读 SQA 科学课程的八年级学生设计。你将学会如何解读数据、识别变量、得出结论并应用所学知识，这些都是自信应对案例分析题所必需的技能。
1. What Is a Case Study in Science? | 什么是科学案例分析？
A case study in science is a detailed examination of a real or simulated situation where scientific concepts can be applied to solve a problem. It often includes experimental data, observations, and background information, asking you to analyse and explain what is happening.
科学中的案例研究是对真实或模拟情境的详细分析，在其中可以应用科学概念来解决问题。案例通常包含实验数据、观察结果和背景信息，要求你分析并解释正在发生的现象。
Case studies test more than just your memory of facts; they assess your ability to think like a scientist. You might need to identify variables, spot trends, evaluate methods, and link evidence to scientific theories.
案例分析不仅测试你对事实的记忆，还评估你是否能像科学家一样思考。你可能需要识别变量、发现趋势、评价实验方法，并将证据与科学理论联系起来。
In the SQA science assessment, case study questions often appear in the problem-solving section. Mastering them means you can use your knowledge in unfamiliar contexts, which is a key skill for further study in biology, chemistry, and physics.
在 SQA 科学评估中，案例分析题常出现在问题解决部分。掌握这类题目意味着你能在不熟悉的情境中运用知识，这是进一步学习生物、化学和物理的关键技能。
2. Steps to Analyse a Case Study | 分析案例的步骤
Start by reading the scenario carefully. Underline the scientific keywords and note any data tables, graphs, or diagrams provided. Ask yourself: what is the main question or problem to be solved?
首先仔细阅读情境描述。划出科学关键词，并注意提供的任何数据表、图表或示意图。问自己：需要解决的主要问题是什么？
Identify the variables—independent (what you change), dependent (what you measure), and control (what you keep the same). This step is crucial for understanding experiments and making fair comparisons.
识别变量——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）。这一步对于理解实验和进行公平比较至关重要。
Next, examine the data for patterns or anomalies. Look for increases, decreases, or sudden changes. Use your scientific knowledge to explain why these patterns might occur.
接下来，检查数据中的模式或异常。寻找增加、减少或突然变化。运用你的科学知识解释这些模式可能出现的原因。
Always write answers using evidence from the case study. For example, instead of saying 'light helps plants grow', say 'the data shows that plants received more light grew taller, with an average increase of 3 cm compared to plants in darkness'. This shows you can use data to back up claims.
回答时始终引用案例中的证据。例如，不要说“光照帮助植物生长”，而要说“数据显示，接受更多光照的植物长得更高，与黑暗环境中的植物相比平均高出 3 cm”。这表明你能够用数据支持论点。
3. Case Study 1 – Plant Growth and Light | 案例一：植物生长与光照
Scenario: A student wanted to find out how different light conditions affect the growth of bean seedlings. Three pots with identical soil and seedlings were placed in three conditions for 7 days: Pot A in complete darkness, Pot B on a windowsill with partial light, and Pot C under a grow lamp for 12 hours daily. The student watered all pots equally and measured the height of each seedling at the end. The table below summarises the results.
情境：一名学生想了解不同光照条件如何影响豆苗的生长。三个装有相同土壤和幼苗的花盆被放置在三种条件下培养 7 天：花盆 A 在完全黑暗中，花盆 B 在窗台上接受部分光照，花盆 C 在每天 12 小时植物生长灯下。学生给所有花盆等量浇水，并在结束时测量每株幼苗的高度。下表汇总了结果。
| Pot | Light Condition | Trial 1 (cm) | Trial 2 (cm) | Trial 3 (cm) |
|---|---|---|---|---|
| A | Darkness | 2.1 | 2.4 | 2.2 |
| B | Partial light | 5.8 | 6.0 | 5.9 |
| C | Full light (grow lamp) | 7.6 | 7.8 | 7.7 |
or Pot A: (2.1 + 2.4 + 2.2) / 3 = 2.23 cm. For Pot B: (5.8 + 6.0 + 5.9) / 3 = 5.90 cm. For Pot C: (7.6 + 7.8 + 7.7) / 3 = 7.70 cm.
首先，计算每个花盆的平均高度以便比较。平均值是将三次测量相加后除以 3。花盆 A：(2.1 + 2.4 + 2.2) / 3 = 2.23 cm。花盆 B：(5.8 + 6.0 + 5.9) / 3 = 5.90 cm。花盆 C：(7.6 + 7.8 + 7.7) / 3 = 7.70 cm。
The independent variable here is the light condition (darkness, partial light, full light), and the dependent variable is the average seedling height. Control variables include the amount of water, type of soil, and type of seed—all kept the same.
这里的自变量是光照条件（黑暗、部分光照、全光照），因变量是幼苗的平均高度。控制变量包括水量、土壤类型和种子类型——均保持不变。
A clear pattern emerges: the more light the seedlings received, the taller they grew. Seedlings in complete darkness showed very little growth, while those under the grow lamp grew the most. This suggests that light is essential for photosynthesis, providing the energy for plants to produce food and grow.
一个清晰的模式显现出来：幼苗接收的光照越多，长得越高。完全黑暗中的幼苗几乎没有生长，而生长灯下的幼苗长得最高。这表明光照是光合作用所必需的，为植物提供能量以制造养分并生长。
If you were asked to improve this experiment, you might suggest using more types of seeds or measuring mass as well as height, to give extra evidence. You could also repeat the whole experiment to ensure reliability.
如果要求你改进这个实验，你可以建议使用更多种类的种子，或除高度外再测量质量，以提供额外证据。你也可以重复整个实验以确保可靠性。
4. Case Study 2 – Factors Affecting Rusting | 案例二：影响生锈的因素
Scenario: A technician set up four test tubes, each containing a clean iron nail. Tube 1 had the nail in tap water open to air. Tube 2 had the nail in boiled water with a layer of oil to keep air out. Tube 3 had the nail in dry air with a drying agent (calcium chloride) to absorb moisture. Tube 4 had the nail in salt water open to air. After one week, the nails were observed for rust.
情境：一名技术人员准备了四支试管，每支装有一根洁净的铁钉。试管 1 中铁钉浸泡在自来水中并敞开放置。试管 2 中铁钉浸泡在煮沸过的水中，并覆盖一层油以隔绝空气。试管 3 中铁钉放在干燥空气中，并放入干燥剂（氯化钙）吸收水分。试管 4 中铁钉浸泡在盐水中并敞开放置。一周后观察铁钉的生锈情况。
| Tube | Conditions | Rust observed? |
|---|---|---|
| 1 | Water + air | Heavy rust |
| 2 | Water only, no air | No rust |
| 3 | Air only, no water | No rust |
| 4 | Salt water + air | Very heavy rust |
To analyse this case study, first identify the purpose: to determine what causes iron to rust. Compare Tube 1 and Tube 2—the only difference is the presence of air. Rust formed only in Tube 1, so air (oxygen) is needed. Compare Tube 1 and Tube 3—the only difference is water. Rust formed only when water was present. Therefore, both water and oxygen are necessary for rusting.
要分析这个案例，首先明确目的：确定铁生锈的原因。比较试管 1 和试管 2——唯一区别是空气是否存在。只有试管 1 生锈，因此空气（氧气）是必需的。比较试管 1 和试管 3——唯一区别是水。只有存在水时才生锈。因此，水和氧气是生锈的必备条件。
Tube 4 had the heaviest rust, which tells us that salt accelerates the rusting process. This is why cars in coastal or wintery areas where salt is used on roads rust faster. The conclusion can be written as: rusting is a chemical reaction requiring iron, water, and oxygen; the presence of salt speeds it up.
试管 4 生锈最严重，这告诉我们盐能加速生锈过程。这就是沿海或冬季撒盐道路上的汽车更容易生锈的原因。结论可以写为：生锈是一种需要铁、水和氧气的化学反应；盐的存在会加速反应。
Always use comparative language when writing answers. For example, 'In Tube 1, the nail rusted heavily, whereas in Tube 2, with no air, no rust formed, showing oxygen is essential.' This makes your reasoning clear.
撰写答案时应始终使用比较性语言。例如，“在试管 1 中，铁钉严重生锈，而在没有空气的试管 2 中却没有生锈，这表明氧气是必需的。”这能使你的推理清晰明了。
5. Case Study 3 – Energy on a Roller Coaster | 案例三：过山车中的能量
Scenario: At a theme park, a roller coaster car of mass 500 kg starts at the top of a hill (point A) at a height of 20 metres. It then drops to the lowest point (point B). Assume no energy is lost to friction or air resistance. The gravitational field strength g is 10 N/kg.
情境：在一个主题公园，一辆质量为 500 kg 的过山车从高 20 m 的山顶（A 点）出发，然后下降到最低点（B 点）。假设没有能量因摩擦或空气阻力而损失。重力场强度 g 取 10 N/kg。
Eₚ = 500 × 10 × 20 = 100 000 J. Since the car is at rest, its kinetic energy (Eₖ) is zero.
在 A 点，过山车具有重力势能（Eₚ），公式为 Eₚ = mgh。代入数据：Eₚ = 500 × 10 × 20 = 100 000 J。由于车静止，其动能（Eₖ）为零。
, we have Eₖ = 100 000 J. The kinetic energy formula is Eₖ = ½mv², so 100 000 = ½ × 500 × v². Solving: 100 000 = 250 v², thus v² = 400, and v = √400 = 20 m/s.
随着过山车下降，势能转化为动能。在 B 点，假设所有势能都已转化为动能，我们有 Eₖ = 100 000 J。动能公式为 Eₖ = ½mv²，因此 100 000 = ½ × 500 × v²。解方程：100 000 = 250 v²，于是 v² = 400，v = √400 = 20 m/s。
This case study demonstrates the principle of conservation of energy. The total mechanical energy remains constant in the absence of non-conservative forces. Even if friction were considered, the energy would still be conserved but some would be transferred to thermal energy, making the car slower at point B.
这个案例展示了能量守恒原理。在没有非保守力的情况下，总机械能保持不变。即使考虑摩擦，能量仍然守恒，但部分能量会转化为热能，使车在 B 点速度变慢。
When answering exam questions on energy, always state which energy transfer is taking place. Use calculations to support your description, and remember to include correct units. For example: 'At the top, the car stores 100 000 J of potential energy; this is transformed into kinetic energy as it falls, reaching a speed of 20 m/s at the bottom.'
在回答关于能量的考题时，务必说明正在发生哪种能量转移。用计算支持你的描述，并记得写出正确的单位。例如：“在顶部，过山车储存了 100 000 J 的势能；下落时势能转化为动能，在底部达到 20 m/s 的速度。”
6. Case Study 4 – Acid Rain and Lake Acidity | 案例四：酸雨与湖泊酸度
Scenario: A scientist monitored the pH level of a lake near an industrial area over several decades. The average pH readings are given below. Pure water has a pH of 7, and values below 7 indicate acidity.
情境：一名科学家监测了一个工业区附近湖泊数十年的 pH 值。平均 pH 读数如下。纯水的 pH 为 7，低于 7 的值表示酸性。
| Year | 1980 | 1990 | 2000 | 2010 | 2020 |
|---|---|---|---|---|---|
| Average pH | 5.8 | 5.2 | 4.9 | 5.5 | 6.1 |
Examine the trend: from 1980 to 2000, the pH decreased from 5.8 to 4.9, meaning the lake became more acidic. This correlates with increased emissions of sulfur dioxide and nitrogen oxides from factories and vehicles, which form acid rain.
观察趋势：从 1980 年到 2000 年，pH 从 5.8 降到 4.9，意味着湖水酸性增强。这与工厂和车辆排放的二氧化硫和氮氧化物增加有关，这些气体形成酸雨。
After 2000, the pH started to rise again, reaching 6.1 by 2020. This improvement likely reflects environmental regulations that reduced air pollution. The data clearly show the link between human activity and the lake's health.
2000 年以后，pH 开始回升，到 2020 年达到 6.1。这一改善很可能反映了减少空气污染的环境法规的作用。数据清楚地显示了人类活动与湖泊健康状况之间的联系。
To fully answer a case study like this, you should state the trend in numbers. For instance, 'Between 1980 and 2000, the lake's pH dropped by 0.9 units, indicating a significant increase in acidity.' Use scientific vocabulary like 'acidification' and 'recovery'.
要完整回答此类案例，应用数字说明趋势。例如，“1980 年至 2000 年间，湖水 pH 下降了 0.9 个单位，表明酸度显著增加。”使用“酸化”和“恢复”等科学词汇。
7. Case Study 5 – Deforestation and Animal Populations | 案例五：森林砍伐与动物种群
Scenario: A study in a tropical region recorded the area of forest cover and the estimated number of Sumatran tigers over a 20-year period. The following table gives the data.
情境：一项在热带地区的研究记录了 20 年间森林覆盖面积和苏门答腊虎的估计数量。下表给出了数据。
| Year | Forest area (km²) | Tiger population |
|---|---|---|
| 2000 | 5 000 | 400 |
| 2005 | 4 200 | 320 |
| 2010 | 3 500 | 250 |
| 2015 | 2 800 | 180 |
| 2020 | 2 200 | 110 |
Analysis begins by noting the pattern: as forest area decreased, the tiger population also fell. The correlation is strong—when forest area halved (from 5000 to 2200 km²), the tiger population decreased from 400 to 110, a drop of nearly 73%.
分析从观察模式开始：随着森林面积减少，老虎数量也下降了。两者之间有很强的相关性——当森林面积减半（从 5000 到 2200 km²），老虎数量从 400 只减少到 110 只，降幅近 73%。
The scientific explanation is that deforestation destroys tigers' habitat and the habitats of their prey, leading to food shortages. Fragmented forests also make it harder for tigers to find mates. Biodiversity loss is a direct result of human activity like logging and land conversion for agriculture.
科学解释是，森林砍伐破坏了老虎的栖息地及其猎物的栖息地，导致食物短缺。碎片化的森林也使老虎更难找到配偶。生物多样性的丧失是人类活动（如伐木和转为农业用地）的直接结果。
A well-structured answer should connect the evidence to ecological concepts. For example: 'The data indicates that habitat loss due to deforestation is the main driver of the tiger population decline, illustrating the importance of forest conservation.'
结构良好的答案应将证据与生态学概念联系起来。例如：“数据表明，森林砍伐导致的栖息地丧失是老虎数量下降的主要驱动因素，这说明了森林保护的重要性。”
8. Case Study 6 – Balanced Diet Evaluation | 案例六：均衡饮食评估
Scenario: A teenager recorded everything she ate in one day, along with the estimated energy and nutrient content. The table shows her intake compared with recommended values.
情境：一名青少年记录了她一天中吃的所有食物，以及估计的能量和营养素含量。表格将其摄入量与推荐值进行了比较。
| Nutrient | Recommended | Her intake |
|---|---|---|
| Energy (kJ) | 8 800 | 11 500 |
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