📚 Planning an Investigation in Chemistry | 化学探究实验的设计与规划
In KS3 chemistry, planning an investigation is the first and most important step before any experiment. A clear plan helps you test an idea, collect reliable results and stay safe in the laboratory. This article explains how to plan a chemistry investigation step by step.
在 KS3 化学中，规划探究实验是开展任何实验前最重要的一步。清晰的计划能帮助你检验想法、收集可靠结果，并在实验室中保证安全。本文将一步步解释如何规划一项化学探究。
1. Asking a Scientific Question | 提出科学问题
Every investigation starts with a clear scientific question. The question should be specific and testable. Instead of asking 'What happens when I heat water?' ask 'How does the temperature of water affect how quickly a sugar cube dissolves?'
每项探究都始于一个清晰的科学问题。问题应当具体且可检验。不要问“加热水会发生什么？”，而应问“水的温度如何影响方糖溶解的快慢？”
A good question usually links two things: something you can change and something you can measure.
好的问题通常将两件事联系起来：一个你可以改变的量和一个你可以测量的量。
2. Writing a Hypothesis | 写出假设
A hypothesis is a prediction based on scientific ideas. It often follows the pattern: 'If the temperature increases, then the sugar will dissolve faster because the particles have more energy.'
假设是基于科学观点的预测。它通常遵循“如果……那么……因为……”的模式：“如果温度升高，那么糖会溶解得更快，因为粒子具有更多能量。”
The hypothesis does not have to be correct; it gives you something to test.
假设并不一定必须正确；它为你提供了需要检验的内容。
3. Identifying Variables | 识别变量
There are three main types of variable: independent, dependent and control. The independent variable is the one you change; the dependent variable is the one you measure; control variables are all the things you keep the same.
变量主要有三类：自变量、因变量和控制变量。自变量是你改变的量；因变量是你测量的量；控制变量是你保持不变的所有条件。
| Variable type 变量类型 | Meaning 含义 | Example 示例 |
|---|---|---|
| Independent 自变量 | The variable you change 你改变的量 | Water temperature 水温 |
| Dependent 因变量 | The variable you measure 你测量的量 | Time to dissolve 溶解时间 |
| Control 控制变量 | The variables you keep the same 保持不变的条件 | Volume of water, mass of sugar, stirring 水的体积、糖的质量、搅拌 |
In a fair test, you change only the independent variable and measure the dependent variable, while keeping all control variables constant.
在公平测试中，你只改变自变量并测量因变量，同时保持所有控制变量不变。
4. Choosing Equipment | 选择实验器材
Choose equipment that can measure your variables accurately. For the dissolving investigation, you may need a thermometer, a stopwatch, a measuring cylinder, a beaker, a balance and a stirring rod.
选择能准确测量变量的器材。在溶解实验中，你可能需要温度计、秒表、量筒、烧杯、天平和玻璃棒。
Always select a measuring instrument with an appropriate scale and range, such as a 100 cm³ measuring cylinder rather than a small beaker with no graduations.
始终选择量程和刻度合适的测量仪器，例如使用 100 cm³ 的量筒，而不是没有刻度的普通小烧杯。
Do not forget safety equipment such as safety goggles and a heat-proof mat.
不要忘记护目镜和隔热垫等安全器材。
5. Writing a Step-by-Step Method | 编写分步实验方法
The method should be written as numbered steps in the correct order. Each step must be clear enough for another person to follow safely.
实验方法应按正确顺序写成编号步骤。每一步必须足够清晰，便于他人安全操作。
Example method:
示例方法：
- 1. Pour exactly 100 cm³ of water into a beaker. 用量筒量取 100 cm³ 水倒入烧杯。
- 2. Heat the water to 20 °C and keep it at this temperature. 将水加热至 20 °C 并保持该温度。
- 3. Add one 5 g sugar cube and start the stopwatch. 放入一块 5 g 方糖并启动秒表。
- 4. Stop the stopwatch when the sugar has completely dissolved. 当糖完全溶解时停止秒表。
- 5. Record the time in a results table. 将时间记录在结果表中。
- 6. Repeat at 30 °C, 40 °C, 50 °C and 60 °C. 分别在 30 °C、40 °C、50 °C 和 60 °C 重复实验。
Using numbered steps makes the method easy to follow and reduces the chance of missing an important action.
使用编号步骤可以使方法更容易遵循，并减少遗漏重要操作的可能。
6. Controlling Risks | 控制实验风险
Before you begin, identify hazards and describe how to reduce risk. In this investigation, hot water can scald, glass can break and spills can make the floor slippery.
开始实验前，要识别危险源并说明如何降低风险。在本实验中，热水可能烫伤、玻璃可能破碎，溢出物可能使地面湿滑。
Wear safety goggles to protect your eyes, use a heat-proof mat under hot apparatus and wipe up spills immediately.
佩戴护目镜保护眼睛，在加热器具下方放置隔热垫，并立即清理溢出液体。
A risk assessment should always be part of your plan, even for simple experiments.
即使简单的实验，风险评估也应始终包含在计划中。
7. Collecting Data and Observations | 收集数据与观察结果
Design a results table before starting the experiment. The table should have columns for the independent variable, the dependent variable and any repeat readings.
开始实验前先设计结果记录表。表格应包括自变量、因变量和重复测量值等列。
Record quantitative data, such as time in seconds, and qualitative observations, such as 'the sugar disappeared'.
记录定量数据（如以秒为单位的时间）和定性观察（如“糖消失了”）。
| Water temperature 水温 (°C) | Trial 1 第1次 (s) | Trial 2 第2次 (s) | Trial 3 第3次 (s) | Mean 平均值 (s) |
|---|---|---|---|---|
| 20 | 180 | 175 | 185 | 180 |
| 30 | 120 | 115 | 125 | 120 |
| 40 | 70 | 65 | 75 | 70 |
| 50 | 40 | 35 | 45 | 40 |
| 60 | 22 | 20 | 24 | 22 |
Always use the same number of decimal places and include units in the column headings.
始终使用相同的小数位数，并在表头中注明单位。
8. Repeating Measurements for Reliability | 重复测量以提高可靠性
Repeat each measurement at least three times and calculate a mean. This reduces the effect of random errors and makes your results more reliable.
每项测量至少重复三次并计算平均值。这可以减少随机误差的影响，使结果更加可靠。
Do not include obvious outliers when calculating the mean, but note them in your evaluation.
计算平均值时不要包含明显异常值，但应在评估中记录它们。
Reliable results are consistent across repeats, so repeating measurements is a key part of good experimental design.
可靠的结果在重复测量中具有一致性，因此重复测量是良好实验设计的关键部分。
9. Making It a Fair Test | 确保公平测试
In a fair test, you change only the independent variable. All control variables must stay the same; otherwise you cannot be sure what caused the change in the dependent variable.
在公平测试中，你只改变自变量。所有控制变量必须保持不变；否则你无法确定是什么引起了因变量的变化。
For example, if you changed both temperature and volume of water, you would not know which one affected dissolving time.
例如，如果你同时改变温度和水的体积，你就无法知道哪一个影响了溶解时间。
List your control variables clearly in the plan and explain how you will keep them constant.
在计划中清楚列出控制变量，并说明如何保持它们不变。
10. Evaluating the Plan | 评估实验方案
After collecting results, evaluate the plan. Ask whether the data support the hypothesis, whether the range of the independent variable was wide enough, and whether any errors occurred.
收集结果后，评估实验方案。思考数据是否支持假设、自变量范围是否足够宽，以及是否出现任何误差。
You could improve the plan by using more precise instruments, taking more repeats or controlling room temperature.
你可以通过使用更精密的仪器、增加重复次数或控制室温来改进方案。
A good evaluation always suggests improvements, not just lists mistakes. This final step helps you become a better scientific planner.
好的评估总是会提出改进建议，而不仅仅是罗列错误。最后这一步能帮助你成为更优秀的科学实验设计者。
Published by TutorHao | Chemistry Revision Series | aleveler.com
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