📚 Year 11 Cambridge IGCSE Physics: Exam Technique and Marking Criteria | Year 11 剑桥物理：答题技巧与评分标准
Success in Cambridge IGCSE Physics (0625) is not only about knowing the content — it also depends on how you present your answers, follow command words, and satisfy the marking criteria. This guide breaks down essential exam techniques for Papers 2, 4 and 6, and explains what examiners look for when awarding marks. Using these strategies will help you avoid common pitfalls and convert your knowledge into top grades.
在剑桥 IGCSE 物理 (0625) 中取得高分，不仅仅取决于你是否掌握知识，还在于你如何呈现答案、遵循指令词以及满足评分标准。本指南详细解析了试卷二、四和六的关键答题技巧，并解释了考官在评分时的关注点。使用这些策略将帮助你避免常见错误，将知识转化为顶尖成绩。
1. Understanding Command Words | 理解指令词
Command words tell you exactly what the examiner expects. 'State' means give a short, factual answer without explanation — e.g. 'State the unit of charge.' Just write 'coulomb (C)'. 'Describe' requires you to say what happens, often using data or observations, but not why. For example, 'Describe the motion of the object' might need 'The object accelerates uniformly from rest for 5 s, then travels at constant speed.' 'Explain' asks for a scientific reason using 'because' or 'due to' — you must link cause and effect with physics principles. 'Calculate' means work out a numerical answer and show your steps. 'Suggest' often appears in unfamiliar contexts: propose a plausible idea based on your physics knowledge. In mark schemes, each command word is linked to specific types of response; if you give a description when an explanation is required, you will lose most of the available marks.
指令词明确告诉你考官的期望。“State”要求给出简短、事实性的答案，无需解释 — 例如“说出电荷的单位”，只需写“库仑 (C)”。“Describe”需要你描述发生了什么，通常要使用数据或观察结果，但不说原因。例如，“描述物体的运动”可能需要“物体从静止开始均匀加速 5 秒，然后以恒定速度运动”。“Explain”要求使用“因为”或“由于”给出科学理由 — 你必须用物理原理将原因和结果联系起来。“Calculate”意味着算出数值答案并展示步骤。“Suggest”常出现在陌生情境中：根据你的物理知识提出一个合理的想法。在评分方案中，每个指令词都对应特定的回答类型；如果要求解释你却给出了描述，你将丢失大部分可得的分数。
2. Reading the Question Carefully | 仔细阅读题目
Before you start writing, underline key terms and quantities. Note the required unit, direction, or whether the answer must come from a graph or table. Many students lose marks by calculating when the question says 'Use the graph to determine...' — you must read values from the graph, not use an equation. Pay attention to plurals: 'Give reasons' means more than one. If a question mentions 'magnitude', a vector answer with direction may not be credited. Look for phrases like 'in terms of...' which guide the variables you must use. In Paper 4, questions often contain multiple parts; each part builds on the previous one, so getting part (a) wrong can affect (b). Double-check that you have answered every sub-question. The mark scheme rewards precise responses to the question as set, not general knowledge.
在动笔之前，划出关键术语和物理量。注意要求的单位、方向，或答案是否必须从图表或表格中获得。很多学生丢分是因为题目说“利用图像确定......”，他们却去计算——你必须从图像中读取数值，而非使用公式。注意复数形式：“给出理由”意味着不止一个。如果题目提到“大小”，给出带有方向的矢量答案可能不得分。留意“用......表述”这样的短语，它指示你必须使用的变量。在试卷四中，题目通常包含多个小问；每个小问都建立在前一问的基础上，因此 (a) 做错可能影响 (b)。务必检查你是否回答了每一个子问题。评分方案奖励与所设问题精确对应的回答，而非泛泛的知识。
3. Using Correct Units and Significant Figures | 使用正确的单位和有效数字
Always include the correct unit with your final numerical answer unless the question already provides it. In IGCSE Physics, missing units can cost 1 mark per question. Use SI units unless instructed otherwise: convert cm to m, grams to kg, minutes to seconds before substituting into formulas. For significant figures, follow the data given: if the least precise measurement has two significant figures (e.g. 2.0 A), your final answer should generally be given to two significant figures (e.g. 6.0 V). In multiplication and division, count significant figures; in addition and subtraction, look at decimal places. Be consistent: writing 5.0 m s⁻² is better than 5 m/s² when the precision matters. The mark scheme often specifies an allowed range and penalises inappropriate significant figures.
始终在最终数值答案后面加上正确的单位，除非题目已经提供。在 IGCSE 物理中，漏写单位每道题可能扣 1 分。除非另有要求，一律使用国际单位制：代入公式前，将厘米转换为米，克转换为千克，分钟转换为秒。关于有效数字，要遵循所给数据：如果最不精确的测量值有两位有效数字（例如 2.0 A），你的最终答案通常也应保留两位有效数字（例如 6.0 V）。乘除运算中，计算有效数字的位数；加减运算中，则看小数点后的位数。保持一致性：当精度重要时，写 5.0 m s⁻² 优于 5 m/s²。评分方案通常会指定一个允许的范围，并对不恰当的有效数字进行扣分。
4. Showing Working in Calculations | 展示计算步骤
Examiners award marks for method, substitution, and final answer. Even if your final answer is wrong, clear working can earn you most of the marks. Always start by writing the relevant formula, then substitute the numbers with their units. Perform the calculation step by step, and write the final answer with its unit. For example:
R = V / I = 12 V / 2.0 A = 6.0 Ω
If you made a calculator error and wrote 60 Ω, you would still get credit for the correct formula and substitution. In multi-step problems, carry through exact values or at least one extra significant figure to avoid rounding errors. Present your working in a logical sequence; examiners cannot award marks for guessing. The mark scheme explicitly lists 'formula', 'substitution', 'calculation', and 'unit' as separate scoring points.考官对方法、代入数据和最终答案分别给分。即使你的最终答案是错的，清晰的步骤也能为你赢得大部分分数。总是先写出相关公式，然后代入带有单位的数值。逐步进行计算，最后写出带单位的答案。例如：
R = V / I = 12 V / 2.0 A = 6.0 Ω
如果你因计算器按错而写成 60 Ω，你仍然会因正确的公式和代入而获得分数。在多步骤问题中，保留精确值或至少多一位有效数字以避免舍入误差。按逻辑顺序呈现你的解题过程；考官无法给猜测的答案打分。评分方案明确将“公式”、“代入”、“计算”和“单位”列为单独的得分点。5. Labelling Diagrams and Graphs | 标注示意图与图表
graphs, label each axis with the physical quantity and its unit separated by a slash, e.g. 'Distance / m' and 'Time / s' ooth line of best fit, either straight or curved. For diagrams, use a sharp pencil and a ruler; circuit diagrams must show correct standard symbols, and components should be connected with straight lines, avoiding gaps. In ray diagrams, use arrows to indicate direction, and label normal lines and angles. Mark schemes award marks for correct axis labels, appropriate scales, accurate plotting, and a well-judged best-fit line. Missing units or poor scales can cost marks even if the data is correct.
在绘制图表时，用斜线分隔的物理量和单位标注每条坐标轴，例如“Distance / m”和“Time / s”。使用占据大部分网格的合理线性刻度，避免 3:10 等别扭的比例。用小叉号 (×) 仔细标记数据点，并画出平滑的最佳拟合线，可为直线或曲线。作图时，使用削尖的铅笔和直尺；电路图必须展示正确的标准符号，各元件应用直线连接，不留空隙。在光线图中，用箭头表示方向，并标注法线和角度。评分方案会根据坐标轴标签正确、比例合理、描点准确以及最佳拟合线恰当来给予分数。即使数据正确，缺少单位或比例不当也会丢分。
6. Answering 'Describe' and 'Explain' Questions | 回答“描述”与“解释”类问题
The distinction between describing and explaining is one of the most common reasons for lost marks. A description should state the observations or trends: 'The temperature rises steadily for 5 minutes, then stays constant.' No reasons are required. An explanation must give a scientific cause: 'The temperature rises because the heater supplies energy, increasing the kinetic energy of particles. It becomes constant at boiling point as the energy is used to break bonds rather than raise temperature.' Use key physics vocabulary such as 'gradient', 'directly proportional', 'upthrust', 'potential difference', and link ideas with 'so', 'therefore', 'because'. In Paper 4, a 3-mark explanation question typically expects three linked logical steps. The mark scheme lists the required steps; if you just repeat the question or give a vague answer, you receive no credit.
描述和解释之间的混淆是最常见的丢分原因之一。描述应陈述观察结果或趋势：“温度稳定上升 5 分钟，然后保持不变。”不需要给原因。解释则必须给出科学原因：“温度上升是因为加热器提供能量，增加了粒子的动能。在沸点温度保持恒定，因为能量用于打破键而不是升高温度。”使用关键物理词汇，如“梯度”、“成正比”、“上推力”、“电势差”，并用“因此”、“所以”、“因为”来连接观点。在试卷四中，一个 3 分的解释题通常期待三个有逻辑关联的步骤。评分方案列出了所需步骤；如果你只是重复题目或给出模糊的答案，将不会得分。
7. Planning Experiments | 设计实验
Paper 6 heavily tests practical planning. You must identify the independent variable (the one you change), the dependent variable (the one you measure), and control variables (keep constant). Describe the equipment, often with a labelled diagram, and state how you will vary the independent variable and measure the dependent one. Include at least five different values, repeat each measurement and calculate an average to improve reliability. Mention how you will avoid parallax error (eye level with scale) and, for timing, use a fiducial marker to judge the start and end more accurately. Where relevant, state precautions: for electrical experiments, limit current to avoid heating effects; for light experiments, use a darkened room. The mark scheme assigns marks for each of these elements, so a structured answer like 'Method: 1... 2... 3...' helps you secure all available points.
试卷六重点考查实验设计能力。你必须确定自变量（你改变的变量）、因变量（你测量的变量）以及控制变量（保持不变）。描述设备，通常附上标注的示意图，并说明你将如何改变自变量和测量因变量。至少包含五个不同值，每个测量重复进行并计算平均值以提高可靠性。说明如何避免视差误差（视线与刻度保持水平），对于计时，使用参考标记更准确地判断开始与结束。在相关情况下，说明注意事项：电学实验中限制电流避免加热效应；光学实验中使用暗室。评分方案为上述每个要素分配分数，因此像“步骤：1... 2... 3...”这样结构化的回答有助于你拿到所有可得的分数。
8. Applying Formulae and Equations | 应用公式与方程
Be fluent with the core equations on the IGCSE Physics formula sheet. For motion:
v = s / t, a = (v - u) / t
For forces and energy:F = m a, W = m g, Eₚ = m g h, Eₖ = ½ m v²
For electricity:V = I R, P = I V, E = I V t
When rearranging, show the step before substituting. For example, to find mass from kinetic energy:m = 2 Eₖ / v²
Then substitute the numbers. The mark scheme often awards a mark specifically for correct rearrangement. If you use a triangle method, be careful to translate it correctly into written work to ensure the examiner can follow your logic. Avoid using non-standard abbreviations: write 'potential difference' or 'p.d.', not just 'V' in a sentence. Units in formulas must be consistent — convert to SI before you begin.要熟练运用 IGCSE 物理公式表中的核心方程。运动学：
v = s / t, a = (v - u) / t
力与能：F = m a, W = m g, Eₚ = m g h, Eₖ = ½ m v²
电学：V = I R, P = I V, E = I V t
进行公式变形时，先展示变形步骤再代入数值。例如，从动能求质量：m = 2 Eₖ / v²
然后再代入数字。评分方案经常专门为正确的公式变形给分。如果你使用三角形法，要小心将其正确转化为书面步骤，以确保考官能跟上你的逻辑。避免使用不标准的缩写：在句子中写“potential difference”或“p.d.”，而不只是“V”。公式中的单位必须一致——在开始前将所有量转换为国际单位。9. Handling Graphs and Data | 处理图表与数据
To find a gradient, choose two points widely spaced on the line (not data points unless they lie exactly on the line). Show the coordinates you use and work out:
gradient = Δy / Δx
State the unit of the gradient, which is the unit of the y-axis divided by the unit of the x-axis. For the intercept, just read the value where the line crosses the axis. When analysing the relationship, use precise language: 'directly proportional' (straight line through origin), 'linear but not proportional' (straight line not through origin), or 'inversely proportional' (curve where product is constant). In data questions, you may need to calculate the mean and range, or comment on an anomalous result. The mark scheme expects the gradient calculated to at least two significant figures and the unit included; a common mistake is giving a gradient without a unit.求斜率时，在线上选择两个相距较远的点（不要使用原始数据点，除非它们恰好落在线上）。展示你使用的坐标并计算：
斜率 = Δy / Δx
写出斜率的单位，即 y 轴单位除以 x 轴单位。截距只需读取直线与坐标轴相交的数值。分析关系时，使用精确的语言：“成正比”（过原点的直线），“呈线性但不成正比”（不过原点的直线），或“成反比”（乘积为常数的曲线）。在数据题中，你可能需要计算平均值和极差，或对异常结果做出评论。评分方案要求斜率至少保留两位有效数字并带单位；最常见的错误是给出的斜率没有单位。10. Common Mistakes to Avoid | 常见错误避免
1. Not converting to SI units: using cm instead of m, g instead of kg, or minutes instead of seconds is a major source of error. 2. Forgetting units: even if the calculation is correct, an omitted unit can cost a mark. 3. Confusing mass and weight: weight is a force measured in newtons (N), mass in kilograms (kg). 4. Using the graph incorrectly: calculating gradients from data points not on the line, or misreading scales. 5. Writing vague explanations: 'It goes up because of energy' fails to specify which energy and the mechanism. 6. Ignoring the number of marks: a 3-mark question cannot be answered with a single sentence. 7. Rounding too early during calculations: keep intermediate values to extra significant figures. The mark scheme punishes these errors consistently, so being aware of them and checking your work can boost your grade.
1. 非国际单位制：用厘米代替米、克代替千克、分钟代替秒是主要的错误来源。2. 忘记单位：即使计算正确，遗漏单位也可能丢分。3. 混淆质量和重量：重量是以牛顿 (N) 为单位的力，质量以千克 (kg) 为单位。4. 错误使用图表：用不在线上的数据点计算斜率，或错误读取刻度。5. 写出模糊的解释：“它因为能量而上升”未能指明哪种能量及其机制。6. 忽视题目分值：一个 3 分的题目不能只用一个句子回答。7. 计算过程中过早舍入：中间值应多保留几位有效数字。评分方案会持续惩罚这些错误，因此意识到它们并检查你的答案可以提高你的成绩。
11. Time Management and Paper Strategy | 时间管理与试卷策略
Paper 2 (Multiple Choice) has 40 questions in 45 minutes — that is slightly over one minute per question. If you get stuck, mark the question and move on; you can return if time allows. Practice working at this pace. Paper 4 (Extended Theory) lasts 1 hour 15 minutes for 80 marks: aim for about 1 mark per minute, then use the remaining 5–10 minutes for checking. Start with the question you feel most confident on to build momentum. Paper 6 (Alternative to Practical) gives 1 hour for 40 marks; read the scenario carefully, as the context often provides clues for your experimental plan. Always leave a few minutes to scan for missing units, decimal points, and command word responses. In the final minute, make sure every question has at least some attempt — you can often pick up marks for a formula or a partial answer. The mark scheme shows that correct fragments still earn partial credit.
试卷二（选择题）在 45 分钟内完成 40 题 — 平均每题略多于一分钟。如果卡住，标记后跳过，有时间再回来。平时练习就要适应这种节奏。试卷四（拓展理论）耗时 1 小时 15 分钟，共 80 分：目标大概是每分钟完成 1 分，然后用剩余的 5–10 分钟检查。从你最有信心的题目开始以建立答题节奏。试卷六（实验替代）在 1 小时内完成 40 分；仔细阅读情境，因为上下文通常为你的实验计划提供线索。总要留出几分钟时间快速检查是否遗漏单位、小数点和指令词对应的回答。在最后一分钟，确保每道题至少有一些尝试 — 你经常能从公式或部分答案中捡到分数。评分方案表明，正确的片段仍然可以获得部分分数。
12. Marking Criteria and Grade Thresholds | 评分标准与分数线
Cambridge IGCSE Physics mark schemes are divided into 'points-based' marking. Each correct piece of information, calculation step, or reasoning link earns a mark. There is no negative marking, so writing something sensible is always better than leaving a blank. For calculation questions, marks are split between formula, substitution, answer, and unit. For descriptive questions, marks are awarded for each key observation or comparison. Grade thresholds vary from session to session, but typical raw mark percentages for the extended tier are roughly: A* around 75–80%, A around 65–70%, B around 55–60%. The exact thresholds depend on paper difficulty, and exam boards combine Paper 2 (weighted 30%) and Paper 4 (weighted 50%) with either Paper 5 or 6 (20%) to determine the final grade. Knowing that every single mark contributes to your final grade should encourage you to pursue marks systematically, using the techniques in this guide to maximise your score.
剑桥 IGCSE 物理的评分方案采用“分点给分”的方法。每个正确的信息、计算步骤或逻辑推理环节都能得分。没有倒扣分，因此写一些合理的内容总比留空要好。对于计算题，分数分配给公式、代入、答案和单位。对于描述性问题，每个关键的观察或比较都会给分。各等级阈值因考季而异，但拓展层级的原始分比例大致为：A* 约 75–80%，A 约 65–70%，B 约 55–60%。确切分数线取决于试卷难度，考试局将试卷二（权重 30%）和试卷四（权重 50%）与试卷五或六（20%）相结合来确定最终等级。知道每一分都对最终等级有贡献，应当鼓励你系统地争取每一分，使用本指南中的技巧来最大化你的得分。
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