📚 Year 9 CIE Physics: Key Points for Experimental/Practical Assessments | Year 9 CIE 物理：实验/实践考核要点
Practical assessments in Year 9 CIE Physics are designed to test your ability to apply scientific methods to real-world situations. You will be expected to plan experiments, take accurate measurements, handle data, draw graphs, and evaluate results. This guide covers the key points you need to master for practical exams or in-class assessments.
Year 9 CIE 物理的实践考核旨在测试你将科学方法应用于实际情境的能力。你需要设计实验、进行准确测量、处理数据、绘制图表并评估结果。本指南涵盖了你需要掌握的关键要点，帮助你应对实践考试或课堂评估。
1. Introduction to Practical Assessments | 实践考核简介
Practical assessments evaluate your experimental skills, usually grouped under planning, observation, measurement, data analysis and evaluation. In CIE Physics, you may carry out a hands-on task or answer questions about an experimental scenario. You need to show safe working practices, careful recording and the ability to draw valid conclusions.
实践考核评估你的实验技能，通常分为规划、观察、测量、数据分析和评估几方面。在 CIE 物理中，你可能会动手操作或回答有关实验情景的问题。你需要展示安全的工作习惯、细致的记录以及从数据中得出有效结论的能力。
Being familiar with common apparatus, graph-plotting conventions and the language of error analysis will make a strong difference to your performance. Remember that marks are awarded not only for the correct result but for showing a logical and safe method.
熟悉常用仪器、绘图规范以及误差分析的表述方式将显著提升你的表现。请记住，评分不仅看结果是否正确，也看你的方法是否逻辑清晰、是否安全。
2. Planning an Investigation | 规划探究实验
1. Write a clear aim: state what you are trying to find out, e.g. "To investigate how the length of a pendulum affects its period."
1. 写下明确的目标：说明你要探究什么，例如 "探究摆长如何影响摆的周期"。
2. Identify the independent variable (the one you change), dependent variable (the one you measure) and control variables (the ones you keep the same).
2. 确定自变量（你改变的变量）、因变量（你测量的变量）和受控变量（你保持不变的变量）。
3. Form a hypothesis: a prediction backed by a brief reason, such as "If the force on a spring increases, the extension will increase because of Hooke's law, provided the elastic limit is not exceeded."
3. 提出假设：一个带有简要理由的预测，例如 "如果施加在弹簧上的力增大，伸长量也会增大，因为遵循胡克定律，只要不超过弹性限度"。
4. Select appropriate equipment and state the range and precision you need. For example, use a 0–10 N spring balance if forces around 5 N are expected; choose a stopwatch that reads to 0.01 s for timing swings.
4. 选择合适的器材，说明你需要的量程和精度。例如，如果预计的力约为 5 N，就选用 0–10 N 的弹簧秤；计时摆动时选用可读到 0.01 s 的秒表。
5. Plan steps to keep control variables constant, such as using the same mass of pendulum bob, same starting angle, and same measuring instruments throughout.
5. 规划保持受控变量的步骤，例如使用相同质量的摆锤、相同的起始角度以及相同的测量工具进行全程实验。
3. Making Measurements | 进行测量
1. Avoid parallax error by placing your eye directly in line with the scale mark. For a measuring cylinder, read the bottom of the meniscus at eye level.
1. 将视线正对刻度线以避免视差。使用量筒时，在视线水平处读取液面的最低点。
2. Record every measurement to the precision of the instrument. A metre ruler usually allows readings to 0.1 cm (1 mm). Write 12.3 cm, not just 12 cm.
2. 记录读数至仪器的精度。米尺通常可读到 0.1 cm (1 mm)。记录为 12.3 cm，而不仅仅是 12 cm。
3. Always check for zero error before using a spring balance, an ammeter or a voltmeter. If the pointer does not rest on zero, record the offset and subtract it from all readings later.
3. 使用弹簧秤、电流表或电压表前务必检查零位误差。如果指针不在零位，记录偏差并在后续所有读数中减去该偏差值。
4. Take at least three repeat readings for each value of the independent variable and calculate the mean. This reduces the impact of random errors and helps identify outliers.
4. 对自变量的每一个取值至少重复测量三次并计算平均值。这可以减少随机误差的影响，也有助于发现异常值。
The table below shows common instruments and their typical measurement precision.
下表列出了常用仪器及其典型的测量精度。
| Instrument | Quantity | Smallest division | Reading uncertainty |
|---|---|---|---|
| Metre ruler | Length | 0.1 cm | ±0.05 cm |
| Measuring cylinder (100 cm³) | Volume | 1 cm³ | ±0.5 cm³ |
| Stopwatch | Time | 0.01 s | ±0.1 s (reaction time) |
| Spring balance (0–10 N) | Force | 0.2 N | ±0.1 N |
| Analogue ammeter (0–1 A) | Current | 0.02 A | ±0.01 A |
4. Recording Data | 记录数据
1. Design a results table before starting the experiment. Include clear column headings with the measured quantity and its unit, using the form "Length, L / cm" or "Time, t / s".
1. 在实验开始前就设计好数据表。表头要清晰，包括测量量和单位，格式如 "长度, L / cm" 或 "时间, t / s"。
2. Record raw data only in the body of the table. Processed data (e.g. averages, speed calculations) should either go in a separate column clearly labelled "Mean time, t̄ / s" or be shown in a later section.
2. 表格主体中只记录原始数据。处理后的数据（如平均值、速度计算）应放在单独的一列，并清楚标注如 "平均时间, t̄ / s"，或在后续部分呈现。
3. Keep the number of decimal places consistent. If your instrument reads to 0.01 s, write 1.20 s, not 1.2 s, so all values show the same precision.
3. 保持小数位数一致。如果你的仪器读到 0.01 s，就写 1.20 s，而不是 1.2 s，以保证所有数据呈现相同的精度。
4. When taking repeated readings, include columns for each trial (1, 2, 3) and a final column for the mean. Circle any obvious outlier that you may exclude from averaging, and note the reason.
4. 进行重复测量时，设置各次试验列（1、2、3）以及最后的平均值列。圈出任何明显的异常值并在计算均值时剔除，同时注明原因。
5. Drawing Graphs | 绘制图表
1. Put the independent variable on the x‑axis and the dependent variable on the y‑axis. Label each axis with the quantity and unit, e.g. "Force, F / N" and "Extension, x / mm".
1. 将自变量放在 x 轴，因变量放在 y 轴。每个坐标轴都要标明物理量和单位，例如 "力, F / N" 和 "伸长量, x / mm"。
2. Choose a scale that makes your plotted points occupy more than half the grid in both directions. Use simple divisions such as 1, 2, 5, 10... per large square; avoid awkward scales like 3 or 7.
2. 选择使描点占满坐标纸在两个方向上都超过一半格子的比例。使用简易的分度，如每大格 1、2、5、10…… 避免像 3 或 7 这样不便计算的比例。
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