📚 Year 10 Cambridge Science: Practical Assessment Key Points | 十年级剑桥科学：实验考核要点
Mastering practical skills is essential for success in Cambridge IGCSE Science. This guide covers the key assessment points you need to know, from planning an experiment to evaluating your results. Whether you are preparing for the practical paper or the alternative to practical written exam, these strategies will help you think like a scientist and avoid common mistakes.
掌握实验技能对于剑桥 IGCSE 科学的成功至关重要。本文涵盖了从设计实验到评估结果的全部关键考核要点。无论你是在准备操作考试还是替代笔试，这些策略将帮助你像科学家一样思考并避免常见错误。
1. Understanding Variables (Independent, Dependent, Controlled) | 理解变量（独立变量、因变量、控制变量）
In any experiment, the independent variable is the factor you deliberately change or test. The dependent variable is what you measure or observe—it depends on the changes you made. All other factors must be kept the same as controlled variables to ensure a fair test.
在任何实验中，独立变量是你故意改变或测试的因素。因变量是你测量或观察的量，它取决于你所做的改变。所有其他因素必须保持不变，成为控制变量，以确保公平测试。
For example, when investigating how temperature affects the rate of a reaction, temperature is the independent variable, the time taken for a colour change is the dependent variable, and the volumes of reactants, concentration, and apparatus are controlled variables.
例如，研究温度如何影响反应速率时，温度是独立变量，颜色变化所需的时间是因变量，反应物的体积、浓度和仪器是控制变量。
You must be able to identify these variables from a description of an investigation and suggest suitable control variables for unfamiliar contexts.
你必须能够从实验描述中识别这些变量，并能为不熟悉的情境建议合适的控制变量。
2. Writing a Clear Step-by-Step Method | 撰写清晰的逐步实验步骤
A good method is written as a series of logical, numbered steps. It should include precise quantities (e.g. 'add 10 cm³ of hydrochloric acid') and describe how to make measurements fairly. Use diagrams if they help, and always mention any safety precautions.
一个好的实验方法应写为一系列逻辑清晰的编号步骤。它应包括精确的用量（例如“加入 10 cm³ 盐酸”），并描述如何公平地进行测量。如果图表有帮助就使用它，并始终提及相关的安全预防措施。
When planning a method, think about how you will change the independent variable, how you will measure the dependent variable, and how you will keep controlled variables constant. Avoid vague words like 'some' or 'a little'; use specific equipment names.
设计实验步骤时，思考你将如何改变独立变量，如何测量因变量，以及如何保持控制变量不变。避免使用“一些”或“少量”等模糊词汇；使用具体的仪器名称。
Example: Instead of 'heat the water', write 'Place the boiling tube in a water bath set to 40 °C and wait for 2 minutes before adding the enzyme'.
示例：不要写“加热水”，而要写“将沸腾管放入设定为 40 °C 的水浴中，等待 2 分钟后加入酶”。
3. Selecting and Using Appropriate Apparatus | 选择和使用合适的仪器
Common apparatus includes beakers, measuring cylinders, thermometers, stopwatches, balances, and volumetric flasks. You should know which piece of equipment gives the most precise measurement for a given task. For example, a burette is more precise than a measuring cylinder for delivering variable volumes of liquid.
常用仪器包括烧杯、量筒、温度计、秒表、天平和容量瓶。你应该知道对于给定任务哪种设备能给出最精确的测量。例如，在移取不同体积的液体时，滴定管比量筒更精确。
Always read the scale at eye level to avoid parallax error. For a thermometer or measuring cylinder, read the bottom of the meniscus. When using a digital balance, zero the balance before placing the object on it.
始终在视线水平处读取刻度以避免视差。对于温度计或量筒，读取凹液面的最低点。使用数字天平时，在放置物体前先调零。
You may be asked to justify the choice of equipment based on the required precision. For instance, if you need to measure 5.0 cm³, a 10 cm³ measuring cylinder is more suitable than a 100 cm³ one.
你可能会被要求根据所需精度来证明设备选择的合理性。例如，如果你需要量取 5.0 cm³，10 cm³ 的量筒比 100 cm³ 的更适合。
4. Making Measurements and Estimating Uncertainty | 进行测量和估计不确定度
Every measurement has an uncertainty, often taken as half the smallest division on an analogue instrument. For a digital instrument, the uncertainty is typically the smallest division shown. In Cambridge papers, you might need to record a measurement with the appropriate number of decimal places, reflecting the precision.
每次测量都有不确定度，对于模拟式仪器通常取最小分度值的一半。对于数字仪器，不确定度通常就是其显示的最小分度。在剑桥考卷中，你可能需要用合适的小数位数记录测量值，以体现精确度。
For repeated readings, calculate the mean and ignore any anomalous results that are clearly different. Anomalous results should not be included in the average, and you should always state that you have excluded them.
对于重复读数，计算平均值并忽略明显不同的异常结果。异常结果不应纳入平均值，并且你应当说明已将其排除。
When timing, start the stopwatch as the reaction begins and stop it the moment the change is observed. To improve repeatability, use a light gate or data logger if available.
计时期间，在反应开始时启动秒表，观察到变化时立即停止。为了提高可重复性，如果可能可使用光门或数据记录器。
5. Recording Data in Tables | 以表格记录数据
Design a table before starting the experiment. The independent variable goes in the left column, and the dependent variable (and any repeated readings and means) goes in the right columns. Each column must have a clear heading with the quantity and its unit, e.g. 'Temperature / °C' or 'Time / s'.
在开始实验前设计表格。独立变量放在左列，因变量（以及任何重复读数和平均值）放在右列。每列必须有清晰的标题，写明物理量和单位，例如“温度 / °C”或“时间 / s”。
Use the same degree of precision for all data in a column. If the stopwatch reads to 0.01 s, write times as 5.00 s, not 5 s. Never leave a unit inside a cell; it belongs only in the heading.
同一列中的所有数据应使用相同的精确度。如果秒表读数为 0.01 s，则把时间写为 5.00 s，而不是 5 s。绝不要把单位留在单元格内，单位只属于标题。
When recording observations, use clear descriptions—colour change from blue to green, bubbles of gas produced, precipitate formed, etc. Avoid ambiguous terms like 'reacted' without detail.
记录观察结果时，使用清晰的描述——颜色从蓝变绿，产生气泡，生成沉淀等。避免使用含义模糊的词语，如没有细节的“反应了”。
6. Plotting Graphs Accurately | 准确绘制图表
Plot the independent variable on the x-axis (horizontal) and the dependent variable on the y-axis (vertical). Choose scales that use at least half the grid in both directions and make it easy to plot points—use simple steps like 1, 2, 5, or 10 units per large square.
将独立变量绘制在 x 轴（横轴）上，因变量绘制在 y 轴（纵轴）上。选择能利用至少一半网格区域的刻度，且易于描点——使用大格代表 1、2、5 或 10 个单位的简单刻度。
Label axes fully with quantity and unit, exactly as in the table heading: 'Temperature / °C' Plot points using small neat crosses (×) or dots with circles. Do not join the points dot‑to‑dot; instead, draw a line or curve of best fit.
完整标注轴名称及单位，与表格标题一致：“温度 / °C”。描点时使用小而整洁的叉号（×）或带圆圈的点。不要逐点连线，而是画出最合适的直线或曲线。
A line of best fit should pass through or near as many points as possible with roughly equal numbers of points above and below the line. Identify and circle any anomalous points that do not fit the trend.
最佳拟合线应穿过或尽可能靠近大多数点，并使线上方和下方的点数大致相等。识别并用圆圈标出不遵循趋势的异常点。
7. Analysing Graphs and Performing Calculations | 分析图表并进行计算
large triangle that covers at least half the line. Read the coordinates of two points on the line (not data points unless they lie exactly on the line).
对于一条直线图，使用公式计算斜率：斜率 = y 的变化量 ÷ x 的变化量。使用一个覆盖至少一半线条的大三角形。读取线上两个点的坐标（非数据点，除非它们正好落在直线上）。
If the graph is a curve, you might be asked to describe the trend: 'As temperature increases, the rate of reaction increases up to an optimum, then decreases.' Use the graph to interpolate values between points or extrapolate beyond the data range only if the question tells you to.
如果图形是一条曲线，你可能会被要求描述趋势：“随着温度升高，反应速率增加至最佳值，随后下降。”使用图表在点之间进行内插，或仅在题目要求时才进行外推。
For calculations, show your working clearly. If you need to find the rate, use 1 ÷ time or change in mass ÷ time. Pay attention to units—rate could be cm³/s, g/min, etc.
计算时要清晰地展示步骤。如果需要求速率，使用 1 ÷ 时间 或 质量变化 ÷ 时间。注意单位——速率可能是 cm³/s、g/min 等。
8. Drawing Conclusions and Evaluating Evidence | 得出结论和评估证据
A conclusion must state what the results show, directly related to the aim. It should refer to the data or graph, e.g. 'The time taken for the colour change decreased as the concentration of acid increased, showing that the reaction was faster at higher concentrations.'
结论必须陈述结果显示了什么，并直接与目标相关。它应提及数据或图表，例如：“颜色变化所需的时间随着酸浓度的增加而减少，表明在较高浓度下反应更快。”
Mention whether the results support the original hypothesis. If they do not, discuss possible reasons. Avoid overstating your findings—don’t claim a general rule unless supported by the data range.
说明结果是否支持原始假设。如果不支持，讨论可能的原因。避免夸大你的发现——除非数据范围内有支撑，否则不要声称普适规律。
Evaluate the quality of evidence by considering repeatability, reproducibility, and whether the experiment was a fair test. Refer to the spread of repeated readings as a measure of reliability.
通过考虑可重复性、再现性以及实验是否为公平测试来评估证据的质量。将重复读数的分布范围作为可靠性的度量。
9. Identifying Sources of Error and Suggesting Improvements | 识别误差来源并提出改进方法
Distinguish between random errors (which cause scatter) and systematic errors (which shift all readings in one direction). Random errors can be reduced by taking more repeats; systematic errors require adjustment of technique or calibration.
区分随机误差（导致数据离散）和系统误差（使所有读数朝一个方向偏移）。随机误差可通过增加重复次数来减少；系统误差则需要调整技术或校准。
Common errors in the lab include heat loss to the surroundings, incomplete mixing, timing inconsistencies, reading meniscus incorrectly, and failing to zero the balance. Improvements could involve using a polystyrene cup as a calorimeter, using a pipette for more accurate volume measurement, or using a data logger for faster response.
实验室中常见的误差包括热量散失到环境中、混合不均匀、计时不一致、凹液面读数错误以及未对天平调零。改进措施可包括使用聚苯乙烯杯作为量热器，使用移液管进行更精确的体积测量，或使用数据记录器以获得更快的响应。
Always suggest at least one specific, practical improvement to the method given. Vague suggestions like 'be more careful' will not gain credit.
对于给定的实验方法，始终至少提出一个具体、实际的改进建议。诸如“更小心点”等模糊的建议是不得分的。
10. Lab Safety Rules and Risk Assessment | 实验室安全规则与风险评估
Always wear safety goggles in a chemistry or physics lab, and tie back long hair. Know the hazard symbols for corrosive, flammable, toxic, and oxidising substances. When heating, point the open end of a test tube away from yourself and others.
在化学或物理实验室中始终佩戴护目镜，并将长发束起。认识腐蚀性、易燃、有毒和氧化性物质的危险符号。加热时，试管开口端应远离自己和他人。
Carry out a risk assessment for any practical: identify the hazard, the risk it poses, and the control measure. For example, using hydrochloric acid—hazard: irritant; risk: skin burns; control: wear gloves and wash off spills immediately.
对任何实验进行风险评估：识别危害、其带来的风险以及控制措施。例如，使用盐酸——危害：刺激物；风险：皮肤灼伤；控制措施：戴手套并立即清洗溢出物。
In biology practicals involving microorganisms, sterilise all equipment and dispose of contaminated materials safely. In physics, be cautious with hot lamps and electrical circuits, avoiding short circuits.
在涉及微生物的生物实验中，对所有设备进行灭菌，并安全处理受污染的材料。在物理实验中，小心使用热灯泡和电路，避免短路。
11. Key Biology Practical Skills | 关键生物实验技能
Microscopy: Prepare a wet mount by placing the specimen on a slide, adding a drop of water, and lowering a coverslip at an angle to avoid air bubbles. Start with the lowest power objective and use the coarse then fine focus. When drawing cells, use a sharp pencil, do not shade, and label with straight lines.
显微镜技术：通过将标本置于载玻片上、加一滴水并将盖玻片以一定角度放下（以避免气泡）来制备临时装片。从最低倍物镜开始，先粗调后细调。绘制细胞图时使用削尖的铅笔，勿涂抹，用直线进行标注。
Food tests: For starch, add iodine solution (blue-black). For glucose, Benedict’s solution and heat (brick-red). For protein, Biuret test (violet). For lipids, ethanol emulsion test (cloudy white). Always include a water control.
食物测试：淀粉：加碘液（蓝黑色）。葡萄糖：本尼迪克特溶液并加热（砖红色）。蛋白质：双缩脲测试（紫色）。脂类：乙醇乳液测试（浑浊白色）。始终包含一个水对照。
Enzyme activity: Measure how fast a substrate disappears or product appears at different pH or temperatures. Keep enzyme concentration and volume constant. Use a water bath to control temperature and add enzyme only after equilibration.
酶活性：测量在不同 pH 或温度下底物消失或产物生成的速率。保持酶浓度和体积不变。使用水浴控制温度，并在温度平衡后再添加酶。
12. Key Chemistry and Physics Practical Skills | 关键化学和物理实验技能
Chemistry – Rates of reaction: Monitor the volume of gas produced using a gas syringe or the time for a cross to disappear under a conical flask. Change concentration or temperature as the independent variable. Record measurements at regular intervals and calculate the initial rate from the steepest part of the graph.
化学——反应速率：使用气体注射器监测产生的气体体积，或记录锥形瓶下的十字消失的时间。将浓度或温度作为独立变量。每隔一定时间记录数据，并从曲线最陡峭的部分计算初始速率。
Chemistry – Titration: he indicator just changes colour. Repeat until concordant results are obtained (±0.1 cm³).
化学——滴定：用待用溶液润洗滴定管。使用移液管量取固定体积。加入指示剂并摇动锥形瓶。终点是指示剂恰好变色之时。重复操作直到获得一致结果（±0.1 cm³）。
Physics – Circuits: nd voltage, then calculate resistance using R = V/I. Note any heating effect and suggest using low currents to minimise it.
物理——电路：将电流表串联、电压表并联。研究电阻时，改变导线长度或添加元件。记录电流和电压，然后使用 R = V/I 计算电阻。注意发热效应，并建议使用低电流以尽量减少热量产生。
Physics – Motion and forces: Use a trolley on a ramp with a light gate to measure speed, or use a stopwatch for timing oscillations. Plot a graph of distance against time and use the gradient for speed. Ensure the ramp is set at a constant angle and friction is minimised.
物理——运动与力：使用斜面上的小车配合光门测量速度，或用秒表计时摆动周期。绘制距离－时间图，用斜率求速度。确保斜面角度保持不变且摩擦力降至最低。
Published by TutorHao | 科学 Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图