KS3 Cambridge Physics: Practical Assessment Key Points | 剑桥KS3物理：实验/实践考核要点

📚 KS3 Cambridge Physics: Practical Assessment Key Points | 剑桥KS3物理：实验/实践考核要点

In the KS3 Cambridge Physics curriculum, practical assessments focus on your ability to apply scientific methods, use equipment correctly, and interpret data. These skills are evaluated through hands-on experiments and written questions about practical work. This guide outlines the essential points you need to master, from safety and variables to graphing and error analysis.

在剑桥 KS3 物理课程中，实践考核侧重于你运用科学方法、正确使用仪器以及解读数据的能力。这些技能通过动手实验和关于实践工作的书面问题进行评估。本指南概述了你需要掌握的关键要点，涵盖安全、变量、图表绘制和误差分析等。

1. Safety in the Lab | 实验室安全

Always wear safety goggles when heating substances, using chemicals, or working with moving parts. Tie back long hair, roll up loose sleeves, and remove dangling jewellery.

在加热物质、使用化学品或操作运动部件时，务必佩戴护目镜。扎起长发，卷起宽松的袖子，并取下悬垂的首饰。

Familiarize yourself with the location of fire extinguishers, fire blankets, and the first aid kit. If you spill anything, clean it up immediately or inform your teacher.

熟悉灭火器、灭火毯及急救箱的位置。如有任何溢出物，应立即清理或告知老师。

Never taste or directly smell chemicals; waft the vapour towards your nose instead. Handle hot objects with tongs and allow them to cool on a heat-resistant mat.

切勿品尝或直接闻化学品；应改为用手扇动气体至鼻端。使用坩埚钳夹取热物体，并将其放置在耐热垫上冷却。

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2. Identifying Variables | 识别变量

The independent variable is the factor you deliberately change in an experiment. The dependent variable is what you measure or observe as a result. All other factors that could affect the outcome must be controlled (control variables) to ensure a fair test.

独立变量是你在实验中刻意改变的因素，因变量是你因此测量或观察到的结果。所有其他可能影响结果的因素都必须受控（控制变量），以确保公平测试。

For example, when investigating how the length of a pendulum affects its period, the independent variable is the string length, the dependent variable is the time for one swing, and control variables include the mass of the bob and the angle of release.

例如，在研究摆长如何影响周期时，独立变量是绳长，因变量是摆动一次的时间，控制变量包括摆锤质量及释放角度。

Writing clear hypotheses and variable tables before starting helps you stay organized. Always state the independent variable, dependent variable, and at least three control variables.

在开始前写下清晰的假设和变量表格有助于保持条理。始终列出独立变量、因变量及至少三个控制变量。

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3. Choosing and Using Equipment | 仪器选择与使用

Select instruments with an appropriate range and sensitivity. For instance, use a thermometer with a range of -10 °C to 110 °C when measuring boiling water, not one that only goes up to 50 °C. Check the smallest scale division to know the precision.

选择量程和灵敏度合适的仪器。例如，测量沸水时使用量程为 -10 °C 至 110 °C 的温度计，而不用最高仅 50 °C 的温度计。查看最小刻度以了解其精度。

When using an ammeter, it must be connected in series; a voltmeter is connected in parallel across the component. Always set multimeters to the correct range before switching on.

使用电流表时，必须串联在电路中；电压表则并联在元器件两端。打开电源前务必先将万用表调至正确档位。

Check for zero errors on measuring devices such as spring balances and rulers. If a spring balance reads 0.2 N when nothing is attached, record the zero error and subtract it from your readings.

检查弹簧秤、直尺等测量设备的零点误差。若弹簧秤空载时读数为 0.2 N，应记录该零点误差，并从后续读数中扣除。

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4. Making Accurate Measurements | 精确测量

To avoid parallax error, position your eye directly in line with the scale when reading liquid levels or ruler markings. For liquids in a measuring cylinder, read the bottom of the meniscus.

为避免视差，读取液位或直尺刻度时眼睛应与刻度保持水平。对量筒中的液体，应读取凹液面底部。

Take repeated measurements and calculate the mean to improve reliability. Discard results that are clearly anomalous before averaging, but note them for evaluation.

进行重复测量并计算平均值，以提高可靠性。在计算均值前应剔除明显异常的结果，但在评价时需注明。

Record readings with the correct number of significant figures based on the instrument’s precision. For example, a ruler marked in millimetres allows measurements to the nearest mm (e.g., 12.3 cm).

根据仪器精度记录读数并保留正确的小数位数或有效数字。例如，毫米刻度直尺可测量至最接近的毫米（如 12.3 cm）。

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5. Recording Data and Observations | 记录数据与观察

Design a results table before starting the experiment. The left column should list the independent variable values, and the right column(s) should list the dependent variable(s) with units in the header.

实验开始前先设计结果表格。左栏列出独立变量的值，右栏列出因变量，表头需注明单位。

Include columns for repeated readings and a column for the calculated mean. Use a pencil and ruler to draw the table neatly.

包含用于重复读数的列以及计算平均值的列。用铅笔和直尺整洁地绘制表格。

Record qualitative observations in full sentences. For example, ‘the solid dissolved rapidly and the solution turned blue’ rather than just ‘blue’.

用完整句子记录定性观察。例如，“固体迅速溶解，溶液变为蓝色”，而非仅写“蓝色”。

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6. Drawing Tables and Graphs | 绘制表格与图表

Graphs should be plotted on graph paper with axes labelled with the quantity and unit, e.g., ‘Time (s)’. The independent variable is conventionally placed on the x‑axis, and the dependent variable on the y‑axis.

应使用坐标纸绘图，坐标轴标出物理量和单位，例如“时间 (s)”。习惯上将独立变量放在 x 轴，因变量放在 y 轴。

Choose scales that use at least half of the graph paper in both directions and go up in regular steps (e.g., 2, 4, 6 or 5, 10, 15). Plot each point as a small, neat cross (×) or dot in a circle.

选择坐标尺度，使数据点至少占满半张坐标纸，并采用等步长（如 2、4、6 或 5、10、15）。每个数据点以小叉 (×) 或带圈圆点标绘。

Draw a line of best fit: a straight line if the points show a linear trend, or a smooth curve if they do not. Do not connect the dots with a zigzag line.

绘制最佳拟合线：若数据点呈线性趋势则画直线，否则画平滑曲线。不要用折线直接逐点相连。

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7. Analyzing Results and Drawing Conclusions | 分析结果与得出结论

Describe the relationship between the variables using phrases such as ‘as the length increases, the time period also increases’. Identify whether the relationship is directly proportional, linear, or non‑linear.

使用类似“随着长度增加，周期也增加”的语句描述变量间关系。判断该关系是正比例、线性还是非线性。

Use data from the graph or table to support your conclusion. For a directly proportional relationship, the line passes through the origin and the ratio of the two quantities is constant.

利用图表或表格中的数据支持结论。对于正比关系，图线经过原点且两物理量的比值恒定。

Compare your findings with the original hypothesis. If the results do not support it, explain

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