Edexcel A-Level Combined Science: Core Practical Skills | 爱德思 A Level 综合科学：核心实验技能

📚 Edexcel A-Level Combined Science: Core Practical Skills | 爱德思 A Level 综合科学：核心实验技能

Success in Edexcel A-Level Combined Science depends not only on understanding the content from biology, chemistry and physics, but also on being able to plan, carry out, record and evaluate practical investigations. This revision article focuses on the core practical skills that appear across Paper 3 and the practical endorsement, such as variables, measurement uncertainty, graphing, calculations and safety.

在爱德思 A Level 综合科学中，成功不仅取决于对生物、化学和物理知识的理解，还取决于能否计划、实施、记录和评估实验探究。本文重点复习 Paper 3 和实验考核中常见的核心实验技能，包括变量、测量不确定度、图表、计算与安全等。

1. Variables and Controls | 变量与对照

In every investigation you must identify the independent variable, the dependent variable and the control variables. The independent variable is the factor you deliberately change; the dependent variable is the factor you measure; control variables are all other factors that must be kept constant so that the test is fair.

在每个实验中，你必须区分自变量、因变量和控制变量。自变量是你有意改变的因素；因变量是你测量的结果；控制变量是所有其他必须保持不变的因素，这样才能保证实验公平。

• Independent variable — changed by the investigator | 自变量——研究者改变的因素
• Dependent variable — measured outcome | 因变量——测量的结果
• Control variables — factors kept constant | 控制变量——保持不变的因素

For example, when investigating how temperature affects the rate of an enzyme-controlled reaction, temperature is the independent variable, the rate of product formation is the dependent variable, and pH, enzyme concentration and substrate concentration are control variables.

例如，在研究温度如何影响酶促反应速率时，温度是自变量，产物生成速率是因变量，而 pH、酶浓度和底物浓度都是控制变量。

2. Planning an Investigation | 实验设计

A good plan begins with a testable hypothesis that links the independent variable to the dependent variable. You should choose a suitable range and interval for the independent variable, for example five temperatures from 10 °C to 50 °C in steps of 10 °C, and include at least three repeats at

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