KS3 WJEC Science: Key Points for Experimental and Practical Assessments | KS3 WJEC 科学：实验/实践考核要点

📚 KS3 WJEC Science: Key Points for Experimental and Practical Assessments | KS3 WJEC 科学：实验/实践考核要点

In KS3 WJEC Science, practical assessments are an essential part of learning. They test your ability to plan experiments, collect and analyse data, and evaluate your methods. This guide walks you through the key points you need to master for success.

在 KS3 WJEC 科学中，实践考核是学习的重要环节。它考察你设计实验、收集与分析数据以及评估方法的能力。本指南将带你掌握成功所需的关键要点。

1. Planning an Investigation | 规划一项调查

Always begin with a clear aim and a testable hypothesis. For example, ‘How does the length of a wire affect its resistance?’ or ‘Does temperature affect the rate of a reaction?’ Your hypothesis should be a prediction you can test with evidence.

始终从明确的目的和可验证的假设开始。例如，‘导线长度如何影响其电阻？’或‘温度是否影响反应速率？’你的假设应是一个可用证据检验的预测。

Identify the independent variable (the factor you change), the dependent variable (the factor you measure) and the control variables (the factors you keep the same). In a wire resistance investigation, the independent variable is wire length, the dependent variable is resistance, and control variables include wire material and thickness.

确定自变量（你改变的因素）、因变量（你测量的因素）以及控制变量（你保持不变的因素）。在导线电阻实验中，自变量是导线长度，因变量是电阻，控制变量包括导线材料和粗细。

Write a step-by-step method using precise language and quantities. For instance, ‘Add 25 cm³ of hydrochloric acid to the beaker’ rather than ‘add some acid’. This enables anyone to repeat your experiment exactly.

用精确的语言和数量编写逐步方法。例如，‘向烧杯中加入 25 cm³ 盐酸’，而不是‘加一些酸’。这能让任何人完全重复你的实验。

2. Variables and Fair Testing | 变量与公平测试

To keep an investigation fair, change only one variable at a time. All other conditions that might influence the outcome must be controlled. For example, when testing how surface area affects reaction rate, keep the mass of solid, temperature and acid concentration constant.

为保证调查公平，每次只改变一个变量。所有可能影响结果的其他条件必须加以控制。例如，在测试表面积如何影响反应速率时，应保持固体质量、温度和酸的浓度不变。

Include a control experiment where the independent variable is removed or set to zero. In a biological investigation, using distilled water instead of an enzyme solution is a common control. This helps confirm that any change is due to the variable you are testing.

设立取消自变量或将其设为零的对照实验。在生物实验中，用蒸馏水代替酶溶液是常见的对照。这有助于确认任何变化都是由你测试的变量引起的。

Fair testing makes your results valid and allows you to draw sound conclusions. Without control, you cannot be sure which variable caused the effect, leading to unreliable data.

公平测试使你的结果有效，并允许你得出合理的结论。没有控制，你就无法确定哪个变量导致了效应，导致数据不可靠。

3. Safety in the Lab | 实验室安全

Always wear safety goggles and a lab coat. Tie back long hair and tuck in loose clothing. Never eat, drink or run in the laboratory, and wash your hands after handling substances.

始终佩戴护目镜和实验服。将长发束起并塞好宽松衣物。切勿在实验室里吃喝或奔跑，并在接触物质后洗手。

When heating substances, use a blue Bunsen burner flame and point the mouth of the test tube away from people. Heat gently and avoid heating sealed containers. Be aware of hot surfaces and use tongs or heat-proof mats.

加热物质时，使用本生灯的蓝色火焰，并将试管口朝向无人处。缓慢加热，避免加热密封容器。注意烫手表面，使用坩埚钳或隔热垫。

Know the location of fire extinguishers, the eyewash station and the first-aid box. If you spill chemicals, inform the teacher immediately. When using acids or alkalis, neutralise spills and rinse skin with plenty of water.

了解灭火器、洗眼器和急救箱的位置。如果溢出化学品，立即报告老师。使用酸或碱时，中和溢出物并用大量水冲洗皮肤。

4. Making Accurate Measurements | 进行准确测量

Choose the appropriate instrument for the quantity you are measuring: a ruler for length, a top-pan balance for mass, a measuring cylinder for volume, and a stopwatch for time. Record both the magnitude and the unit, and read scales at eye level to avoid parallax error.

选择适合待测量的仪器：用尺子量长度，用托盘天平称质量，用量筒测体积，用秒表计时间。记录数值和单位，并在视线水平处读取刻度以避免视差。

Estimate the reading to half of the smallest scale division. For a ruler with 1 mm divisions, you can estimate to ±0.5 mm. Repeat readings to increase reliability and spot anomalies. When timing, measure multiple oscillations and then divide to reduce human reaction-time error.

估读到最小刻度的二分之一。对于分度为 1 mm 的尺子，可估读到 ±0.5 mm。重复读数以提高可靠性并发现异常值。在计时时，测量多次摆动然后求平均，以减少人体反应时间误差。

上表概括了常见的测量仪器及其精度。始终察看仪器量程和精度，并记录不确定性。清晰的记录有助于后续分析和评估。Published by TutorHao | KS3 Science Revision Series | aleveler.com

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