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

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

In Year 7 SQA Engineering, case study practical exercises are an exciting way to explore how engineers solve real-world problems. You will step into the role of a junior engineer, working through a design challenge from start to finish. This article guides you through a complete case study, using a rubber-band powered car as our main project.

在七年级 SQA 工程课程中，案例分析实战演练是探索工程师如何解决现实问题的一种令人兴奋的方式。你将扮演一名初级工程师，从头到尾完成一项设计挑战。本文将通过一个完整的案例分析来引导你，以橡皮筋动力小车作为我们的主要项目。

You will learn to apply the engineering design process, from identifying a problem to testing and improving your final creation. Each stage will be explained with clear steps and practical tips, just like an engineer’s notebook. Ready to begin? Let’s get started on your first engineering mission.

你将学习如何应用工程设计过程，从明确问题到测试并改进最终作品。每个阶段都会像工程师的笔记本一样，用清晰的步骤和实用的提示加以说明。准备好开始了吗？让我们开启你的第一个工程任务吧。

1. Understanding the Engineering Design Process | 理解工程设计过程

Engineering is not just about building things; it is a systematic way of thinking and solving problems. The engineering design process is a cycle that engineers use to create solutions that meet specific needs. It usually involves steps like Ask, Imagine, Plan, Create, Test, and Improve.

工程并不仅仅是制造东西，它是一种系统化的思考和解决问题的方式。工程设计过程是工程师用来创造满足特定需求的解决方案的循环流程。它通常包括提问、构思、计划、创造、测试和改进等步骤。

In your case study, you will follow this cycle to design a small vehicle that can travel a set distance using only a rubber band as a power source. This is a classic Year 7 challenge that combines mechanics, materials, and creative problem-solving. The process is more important than the final product; you will record every decision and observation.

在本次案例分析中，你将遵循这一循环来设计一辆仅以橡皮筋为动力源、能行驶设定距离的小车。这是一项经典的七年级挑战，融合了力学、材料和创造性解决问题的能力。过程比最终产品更重要；你将记录每一个决定和观察结果。

Always remember that failure is a normal part of the cycle. If your first prototype does not work as expected, you will analyse why and improve it. This is called iteration, and it is how the best designs evolve. Your teacher will assess not only the car but also your documentation and reflection.

请始终记住，失败是这一循环的正常组成部分。如果你的第一个原型没有如预期那样工作，你将分析原因并加以改进。这叫做迭代，也是最佳设计演进的方式。老师不仅会评估小车，还会评估你的文档记录和反思。

2. Defining the Design Brief | 定义设计任务书

A design brief is a short statement that clearly describes the problem you need to solve. It includes the goal, the constraints, and the criteria for success. For our case study, the brief reads: ‘Design and build a vehicle powered by a single rubber band that can travel at least 3 metres on a smooth, level floor.’

设计任务书是一份简短陈述，清楚地描述你需要解决的问题。它包括目标、限制条件和成功标准。在我们的案例分析中，任务书写道：“设计并制作一辆由单根橡皮筋驱动的车辆，能够在光滑水平地板上行驶至少 3 米。”

Constraints are the limits you must work within. Here, the only power source is a stretched rubber band; no motors, batteries, or pushing are allowed. The car must be self-contained and start from rest. You may use simple materials like cardboard, plastic wheels, wooden axles, and tape.

限制条件是你必须遵守的界限。这里唯一的动力源是拉长的橡皮筋，不允许使用电机、电池或手推。小车必须是独立的，并从静止开始起步。你可以使用卡纸、塑料轮子、木轴和胶带等简单材料。

Success criteria help you know when you have done a good job. The car must travel over 3 metres in a straight line, and the design must be stable and reusable. Additional challenges might include carrying a small payload, such as a few coins, which you can try as an extension.

成功标准能帮助你判断何时做得好。小车必须沿直线行驶超过 3 米，并且设计必须稳定且可重复使用。额外的挑战可能包括携带一个小载荷，比如几枚硬币，你可以将此作为拓展尝试。

3. Researching Existing Solutions | 研究现有解决方案

Before you start drawing your own ideas, it is wise to look at what already exists. Research might include studying toy cars, balloon-powered racers, or simple rubber-band vehicles you can find in books or online. This is not copying; it is learning from proven mechanisms.

在你着手绘制自己的想法之前，明智的做法是先看看现有的方案。研究可以包括观察玩具车、气球动力赛车，或者你能在书本或网络上找到的简易橡皮筋车辆。这不是抄袭，而是从成熟机制中学习。

Pay attention to how energy is stored and released. In a rubber-band car, potential energy is stored when you twist or stretch the band. When released, this energy turns the axle. Notice where friction is minimised, for example by using smooth axles or lubricated joints.

注意能量是如何储存和释放的。在橡皮筋小车中，当你扭转或拉伸橡皮筋时，势能被储存起来。释放时，这一能量驱动车轴转动。留意哪里减少了摩擦，例如通过使用光滑的车轴或润滑过的连接处。

Record your findings in a simple research log. You can sketch interesting designs and label the key features. This background knowledge will feed directly into your brainstorming session and help you avoid common pitfalls, such as a chassis that is too heavy or wheels that wobble.

将你的发现记录在一个简单的研究日志中。你可以画出有趣的设计并标注关键特征。这些背景知识将直接助益你的头脑风暴环节，并帮助你避免常见陷阱，比如底盘过重或轮子摇晃。

4. Brainstorming and Idea Generation | 头脑风暴与构思创意

Now it is time to let your imagination run. On a blank sheet of paper, sketch every concept that comes to mind—no matter how wild. Aim for at least three distinctly different designs. You might think of a simple frame with an axle-mounted rubber band, or a reel mechanism that unwinds a string.

现在到了发挥想象力的时候。在一张白纸上，画出你想到的每一个概念——无论有多么天马行空。目标是至少画出三种截然不同的设计。你或许会想到一个带轴装橡皮筋的简单框架，或者一个通过释放绳子来驱动卷轴的机构。

Use rapid sketching techniques: draw light outlines, add labels, and indicate where forces will act. Consider how you will transmit energy from the rubber band to the wheels. Common methods include direct winding around the axle, gear systems made from cardboard discs, or friction drives.

使用快速草图技法：画出浅淡轮廓，添加标注，并标明力的作用点。考虑如何将橡皮筋的能量传递到车轮。常见方法包括直接缠绕在轴上、用卡纸圆盘制作的齿轮系统，或者摩擦传动。

During brainstorming, do not judge ideas yet. The goal is quantity and variety. A design that seems silly at first might hold the seed of a brilliant solution. Your teacher may ask you to explain each concept, so be ready to say what you think the advantages and disadvantages might be.

在头脑风暴期间，先不要评判想法。目标是追求数量和多样性。一个起初看似可笑的设计，可能蕴藏着出色解决方案的种子。老师可能会要求你解释每一个概念，因此要准备好说出你认为可能的优缺点。

5. Evaluating and Selecting a Concept | 评估和选择概念方案

Once you have a collection of ideas, it is time to think critically. Create a simple decision matrix to compare your concepts against the design criteria. List criteria such as ‘ease of construction’, ‘predicted distance’, ‘stability’, and ‘use of materials’. Score each idea from 1 (poor) to 5 (excellent).

一旦你收集了一堆想法，就到了批判性思考的时候。创建一个简单的决策矩阵，将你的概念与设计标准进行比较。列出诸如“搭建难易度”、“预估行驶距离”、“稳定性”和“材料使用”等标准。给每个想法打分，从 1 分（差）到 5 分（优）。

A matrix helps you choose a design based on evidence rather than just a gut feeling. For example, a direct axle-wrap design might score high on simplicity but low on reliability because the band could slip. A reel-and-string setup might offer more controlled energy release but be trickier to build.

决策矩阵能帮助你基于证据而非仅仅直觉来选择设计。例如，直接绕轴式设计可能在简洁性上得分高，但在可靠性上得分低，因为橡皮筋可能会打滑。卷轴拉线式设计或许能实现更可控的能量释放，但构建起来更棘手。

Select the highest-scoring concept as your primary design. You are allowed to combine the best features from two ideas. Write a short justification for your choice, linking it to the brief and your research. This decision forms the foundation of the rest of your project.

选择得分最高的概念作为你的主要设计。你可以将两个想法的最佳特征结合起来。为你的选择写一份简短的理由说明，将其与任务书和研究联系起来。这一决定构成了你项目后续部分的基础。

6. Developing the Specification | 制定详细规格

A design specification is a detailed list of exactly what your product must do and the features it must have. It turns the broad brief into measurable targets. For the rubber-band car, your specification might include: total mass under 200 g, wheel diameter between 5 cm and 8 cm, and the ability to roll freely for 3 m after the band is fully unwound.

设计规格是一份详细清单，精确说明你的产品必须具备的功能和特性。它将宽泛的任务书转化为可衡量的目标。对于橡皮筋小车，你的规格可能包括：总质量低于 200 克，轮子直径在 5 厘米到 8 厘米之间，并且橡皮筋完全释放后能自由滑行 3 米。

Specifications also cover materials and dimensions. You might specify that the chassis must be made from corrugated cardboard for stiffness, that axles should be 3 mm wooden dowels, and that all joints must be secured with masking tape. Being precise now saves time later.

规格还涵盖材料和尺寸。你可能指定底盘必须由瓦楞纸板制作以确保刚性，车轴应为直径 3 毫米的木圆棒，所有连接处需用纸胶带固定。现在做到精确，可以节省以后的时间。

Think about safety and user requirements too. The car should have no sharp edges, and the rubber band must be easy to wind without snapping. If the vehicle will carry a payload, specify how the coins will be held securely. A clear specification is like a contract between you and your design challenge.

还要考虑安全性和用户需求。小车不应有锋利边缘，橡皮筋必须易于卷绕而不突然断裂。若车辆将搭载载荷，应说明硬币如何被稳妥固定。一份清晰的规格就像你与设计挑战之间的一份合同。

7. Technical Drawing and Modelling | 技术绘图与建模

Before cutting any materials, create a scale drawing of your chosen design. Use a ruler and pencil to produce orthographic views: a top view and a side view. Label all parts with their materials, dimensions, and how they connect. Even a sketch to scale is a powerful communication tool.

在裁剪任何材料之前，先为你选定的设计绘制一张比例图。用尺子和铅笔画出正交视图：俯视图和侧视图。用材料、尺寸和连接方式标注所有零件。即使是按比例绘制的草图，也是一种强大的沟通工具。

If you have access to a simple CAD program or even Minecraft, you can build a virtual model. Modelling lets you spot clashes, such as wheels rubbing against the frame. It also allows you to experiment with different wheelbases and chassis shapes without wasting physical supplies.

如果你能使用简易 CAD 软件甚至是我的世界这类游戏，你可以搭建一个虚拟模型。建模能帮你发现冲突，比如车轮摩擦车架。它还能让你在不浪费实物材料的情况下试验不同的轴距和底盘形状。

Calculate key quantities to support your design. Estimate the distance the car might travel using the energy stored in the rubber band. Although the full formula is complex, you can use a simplified idea: more initial turns of the band generally mean more stored energy and greater distance, assuming friction is low.

计算关键量以支持你的设计。利用橡皮筋中储存的能量估算小车可能行驶的距离。虽然完整公式很复杂，但你可以使用简化概念：假设摩擦力很低，初始时橡皮筋缠绕的圈数越多，通常意味着储存的能量越多，行驶距离也越远。

Distance ∝ Number of twists (for low friction)

行驶距离 ∝ 扭转圈数（在低摩擦条件下）

8. Building the Prototype | 制作原型

Now the hands-on fun begins. Gather your materials according to the specification: cardboard sheets, wooden skewers for axles, plastic bottle caps for wheels, rubber bands, scissors, and tape. Work carefully and measure twice before cutting. Accuracy in this stage saves much frustration later.

现在动手的乐趣开始了。依照规格收集材料：卡纸板、用作车轴的木签、用作轮子的塑料瓶盖、橡皮筋、剪刀和胶带。仔细操作，裁剪前测量两次。这一阶段的精确性可以避免日后的许多挫折。

Start with the chassis: cut a rectangular base and make small holes for the axles. Ensure the axles are parallel so the car rolls straight. Attach the wheels securely; if they slip, use a dab of glue or tape around the axle. For the rubber-band mechanism, fix one end to the front axle and the other to the chassis or the rear axle, depending on your design.

从底盘开始：裁剪一个矩形底板，并为车轴打小孔。确保车轴平行，这样小车才能直线行驶。牢固地安装车轮；如果车轮打滑，在轴周围涂一点胶水或缠上胶带。至于橡皮筋机构，将一端固定在前轴，另一端固定在底盘或后轴上，取决于你的设计。

Test the mechanism before finalising. Wind the rear axle and watch how the band tightens. Let it go and check that the energy transfers smoothly to the wheels. If the band rubs on the chassis, a small notch or a piece of drinking straw as a guide can reduce friction.

在最终完成前测试机构。转动后轴，观察橡皮筋如何张紧。松开后检查能量是否平稳地传递到车轮。如果橡皮筋摩擦底盘，可以开一个小槽口或用一小段吸管作为导轨来减少摩擦。

9. Testing the Prototype | 测试原型

Set up a clear, flat runway and mark a starting line. Use a metre stick or tape measure to mark the 3-metre target line. Wind the rubber band a set number of turns—say, 20 turns—and record this number. Release the car gently without giving it a push, and observe its motion.

找一条干净平坦的跑道，并标记起跑线。用米尺或卷尺标出 3 米目标线。将橡皮筋卷绕一定圈数——例如 20 圈——并记下这个数字。轻轻地释放小车，不要推它，然后观察它的运动。

Measure the distance travelled from the starting line to where the car stops. Also note the car’s path: did it veer left or right? Did the rubber band slip? Was there any visible wobble in the wheels? Write everything down in a testing log. Repeat the test at least three times for reliability.

测量从起跑线到小车停止处的行驶距离。同时注意小车的行驶路径：它是否向左或向右偏？橡皮筋是否打滑？车轮是否有明显晃动？将一切记录在测试日志中。为了可靠性，至少重复测试三次。

Calculate the average distance and compare it against the 3-metre target. The table below shows a sample set of results. Use your own data to find patterns and identify the weakest part of the design.

计算平均距离，并将其与 3 米目标进行比较。下表显示了一组样本结果。使用你自己的数据来找出模式，并识别设计中最薄弱的部分。

Trial / 试验	Turns / 圈数	Distance (m) / 距离 (米)	Notes / 备注
1	20	2.45	Slight right turn / 轻微右转
2	20	2.60	Straight / 直线
3	20	2.30	Wheel wobble / 车轮晃动
Average / 平均		2.45

10. Analysing Results and Iterating | 分析结果并迭代

Look at your testing data and ask: why did the car not reach 3 m? Perhaps friction in the axles was too high, or the rubber band was too weak. Maybe the wheels were not perfectly round, causing energy loss. Pinpoint the most likely cause and brainstorm a modification.

查看你的测试数据并问自己：为什么小车没有达到 3 米？也许是车轴摩擦力太大，或者橡皮筋太弱。也许轮子不够圆，导致能量损失。找出最可能的原因，并构思一个修改方案。

Typical improvements include lubricating the axles with a tiny bit of candle wax or soap, using larger wheels to cover more ground per revolution, or adding a bearing sleeve made from a drinking straw to reduce twist. Make one change at a time so you can see its effect clearly.

典型的改进措施包括用少量蜡烛蜡或肥皂润滑车轴，使用更大轮子以提高每圈行进距离，或添加用吸管制成的轴承套以减少扭转。每次只做一处改动，这样你就能清楚地看到它的效果。

After making a change, test again and record new distances. Compare the before and after results. This cycle of test, analyse, and redesign is the heart of engineering. You might need to go through several loops before the car reliably reaches the target.

做出改动后，再次测试并记录新的行驶距离。对比改动前后的结果。这种测试、分析、再设计的循环正是工程学的核心所在。你可能需要经历多次循环，小车才能稳定地达到目标。

Also, reflect on what you learned about material properties. For instance, cardbord can bend under stress, while a thin plywood chassis might be stiffer but heavier. Every material choice is a trade-off. Note these insights in your log; they show deep thinking.

此外，反思你对材料特性的了解。例如，卡纸在受力时可能会弯曲，而薄胶合板底盘可能更硬但更重。每一种材料选择都是一种权衡。在你的日志中记下这些见解；它们体现了深层次的思考。

11. Communicating the Solution | 沟通解决方案

Engineers must share their work clearly. Prepare a short presentation or poster that summarises your entire case study. Include your design brief, initial sketches, chosen concept with justification, build photos, test results table, and a graph of improvements over trials.

工程师必须清晰地分享他们的工作。准备一个简短的展示或海报，总结你的整个案例分析。包括你的设计任务书、初期草图、所选概念及理由、制作过程照片、测试结果表格，以及试车过程中改进情况的图表。

A graph of distance vs. trial number can effectively show your iteration progress. Use a bar chart or line graph. Label the axes clearly: the x-axis shows trial number, and the y-axis shows distance in metres. This visual helps others quickly grasp your development journey.

一幅距离与试车次数的关系图能有效展示你的迭代进展。使用条形图或折线图。清晰地标注坐标轴：x 轴表示试车序号，y 轴表示以米为单位的距离。这种可视化有助于他人快速了解你的开发历程。

Write short, technical sentences for your presentation. Use terms you have learned: potential energy, friction, chassis, iteration, and specification. Be honest about challenges and celebrate your improvements. Communication is a vital engineering skill alongside building and testing.

为你的展示撰写简短的技术性语句。运用你学到的术语：势能、摩擦、底盘、迭代和规格。诚实地面对挑战，并庆祝你的改进。沟通是与搭建和测试同样至关重要的工程技能。

12. Real-World Application: The Mars Rover Case | 实际应用：火星车案例

To see engineering case studies in action, look at NASA’s Mars rovers like Perseverance. Engineers faced a similar process: define the mission (study Martian rocks), design within tight constraints (weight, power, extreme temperatures), build prototypes, test in Mars-like deserts on Earth, and iterate relentlessly.

要想看到真实世界中的工程案例分析，可以看看 NASA 的火星漫游车，如毅力号。工程师们经历了类似的过程：定义任务（研究火星岩石），在严格限制条件下进行设计（重量、电力、极端温度），制作原型，在地球上与火星相似的沙漠中进行测试，并不断迭代。

When the first rover designs failed in sand traps, engineers analysed the data, redesigned the wheel treads, and prepared new navigation algorithms. Every bit of testing feedback was recorded and used to improve the next version. This mirrors your own humble rubber-band car project.

当最初的火星车设计陷入沙坑时，工程师们分析数据，重新设计车轮花纹，并开发了新的导航算法。每一点测试反馈都被记录下来，并用于改进下一个版本。这与你这次朴素的橡皮筋小车项目如出一辙。

Understanding that even space exploration relies on the same design cycle you used can be hugely motivating. The skills you are building—creative thinking, systematic testing, documentation, and teamwork—are the very ones that put rovers on another planet. Keep your case study notes; they are the beginning of your engineering portfolio.

明白即使是太空探索也依赖于你所使用的同一个设计循环，这会带来巨大的激励。你正在培养的技能——创造性思维、系统化测试、文档记录和团队合作——正是将火星车送上另一颗星球的能力。保管好你的案例分析笔记，它们是你工程作品集的开端。

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