📚 Year 7 OCR Science: Key Practical Skills & Assessment Tips | Year 7 OCR 科学：实验与实践考核要点
In Year 7 OCR Science, practical work is at the heart of learning. You will be assessed not only on what you know, but also on how you plan, carry out and evaluate experiments. This guide covers the essential practical skills and assessment tips to help you succeed in your practical assessments.
在 Year 7 OCR 科学课程中，实验操作是学习的核心。评估不仅考查你的知识，还考查你如何计划、实施和评价实验。本指南涵盖了关键的实验技能和考核要点，助你在实践考核中取得成功。
1. Lab Safety Rules | 实验室安全规则
Always wear safety goggles when using chemicals, heating substances or handling glassware. Tie back long hair, tuck in loose clothing and wear closed-toe shoes. Never run in the laboratory and keep your work area tidy to avoid trips and spills.
在使用化学品、加热物质或操作玻璃器皿时，务必佩戴护目镜。将长发束起，扎好宽松的衣物，并穿不露趾的鞋子。切勿在实验室内奔跑，保持工作区域整洁，以防绊倒或溅洒。
Know the location of the fire extinguisher, fire blanket and eye wash station. Report all accidents and spills to your teacher immediately, no matter how small. Never taste or smell chemicals directly – use the ‘wafting’ technique if told to detect an odour.
熟悉灭火器、灭火毯和洗眼站的位置。任何事故或溅洒，无论多小，都要立即向老师报告。切勿直接品尝或闻化学药品——如需要闻气味，请使用“扇闻”法。
Always wash your hands after practical work, even if you wore gloves. If you break glassware, tell the teacher and do not pick up pieces with bare hands.
实验结束后务必洗手，即使戴了手套。如果打破玻璃器皿，告知老师，不要徒手捡拾碎片。
2. Identifying and Using Laboratory Equipment | 识别和使用实验仪器
Common equipment includes: a beaker for mixing and heating liquids, a conical flask for swirling safely, a measuring cylinder to measure liquid volume, a Bunsen burner for heating, a tripod and gauze to support apparatus over a flame, a heat-proof mat, a thermometer, a stopwatch and an electronic balance.
常见仪器包括：烧杯用于混合和加热液体，锥形瓶用于安全振荡，量筒测量液体体积，本生灯用于加热，三脚架和石棉网在火焰上方支撑装置，隔热垫，温度计，秒表和电子天平。
When measuring liquid volume, place the measuring cylinder on a flat surface and read the scale at eye level. For water and clear liquids, use the bottom of the curved surface (meniscus). Always pour chemicals carefully to avoid spills.
测量液体体积时，将量筒放在水平台面上，眼睛与刻度平视。对于水及透明液体，读取弯月面底部。倾倒化学品时务必小心，避免溅洒。
Learn the names and uses of other items such as a spatula for solids, a pipette for transferring small liquid amounts, a test tube and test tube rack, and a funnel for filtering. Drawing accurate, labelled diagrams of apparatus is also a key skill.
学习其他用品的名称和用途，如药匙取固体、胶头滴管转移少量液体、试管和试管架、漏斗进行过滤。绘制准确、标注清晰的仪器图样也是一项重要技能。
3. Using a Bunsen Burner | 使用本生灯
A Bunsen burner is used to heat substances safely. Before lighting, check that the rubber tubing is not cracked and the air hole is closed. Place the burner on a heat-proof mat, connect to the gas tap, and light the splint before turning on the gas.
本生灯用于安全加热物质。点火前，检查橡胶管有无破损，确保气孔关闭。将本生灯放在隔热垫上，连接煤气龙头，先用点水条点火，再打开煤气。
With the air hole closed, a yellow ‘safety flame’ appears – it is visible and cooler. To heat efficiently, open the air hole slowly to produce a blue ‘heating flame’, which has a noisy inner cone and is much hotter. Always use the blue flame for heating, and never leave the flame unattended.
气孔关闭时，产生黄色“安全火焰”——可见且温度较低。为了高效加热，缓慢打开气孔产生蓝色“加热火焰”，其内层锥形焰温度高且有啸叫声。加热时始终使用蓝色火焰，切勿让火焰无人看管。
After heating, turn off the gas and let the burner cool. Remember that a hot tripod and gauze remain hot for a while – handle with tongs or allow to cool fully. Never point the open end of a test tube at yourself or others when heating.
加热结束后，关闭煤气，让本生灯冷却。注意三脚架和石棉网会保持高温一段时间——用坩埚钳夹取或待其完全冷却。加热试管时，管口切勿对着自己或他人。
4. Making Measurements and Units | 测量与单位
In science, you must measure accurately and use correct units. Length is measured in metres (m), centimetres (cm) or millimetres (mm). Mass is measured in grams (g) or kilograms (kg). Volume of liquids is measured in millilitres (mL) or cubic centimetres (cm³), where 1 mL = 1 cm³.
在科学中，你必须准确测量并使用正确单位。长度单位是米 (m)、厘米 (cm) 或毫米 (mm)。质量单位为克 (g) 或千克 (kg)。液体体积单位为毫升 (mL) 或立方厘米 (cm³)，其中 1 mL = 1 cm³。
Temperature is recorded in degrees Celsius (°C) using a thermometer. Time is measured in seconds (s) with a stopwatch. Always include the unit when writing a result, and read instruments to the nearest scale division – for example, a thermometer with 1°C markings can be read to ±0.5°C.
温度用温度计记录，单位摄氏度 (°C)。时间用秒表测量，单位秒 (s)。记录结果时务必写上单位，并读取仪器的最小刻度——例如，刻度为 1°C 的温度计可读到 ±0.5°C。
Repeat measurements improve reliability. When you repeat a reading, calculate the mean (average) by adding all values and dividing by the number of readings. Identify and discard anomalous results that do not fit the pattern before averaging.
重复测量能提高可靠性。当你重复测量后，计算平均值（将所有数值相加，除以读数次数）。在求平均前，识别并剔除不符合规律的异常值。
5. Variables: Independent, Dependent and Control | 变量：独立变量、因变量与控制变量
Every experiment has three types of variable. The independent variable is the one you deliberately change. The dependent variable is what you measure or observe. Control variables are all the factors you keep the same to make the test fair.
每个实验都有三种变量。独立变量是你故意改变的那个变量。因变量是你测量或观察的结果。控制变量是保持恒定以使实验公平的其他所有因素。
For example, in ‘How does water temperature affect the time taken for sugar to dissolve?’, the independent variable is the water temperature (°C), the dependent variable is the time taken for sugar to dissolve (s), and control variables include the amount of water, the amount of sugar, the stirring speed and the type of sugar used.
例如，在“水温如何影响糖溶解所需时间？”中，独立变量是水温 (°C)，因变量是糖溶解所需时间 (s)，控制变量包括水的体积、糖的质量、搅拌速度和所用的糖的种类。
You must only change one independent variable at a time. If you change more than one, you will not know which one caused the effect. Always list your variables before starting an experiment and make a plan to control them.
你每次只能改变一个独立变量。如果改变多个，就无法确定是哪一个造成的影响。开始实验前，务必列出你的变量，并制定控制它们的计划。
6. Designing a Fair Test | 设计公平实验
A fair test is one where only the independent variable affects the dependent variable. All other conditions must be kept identical. This allows you to draw valid conclusions about cause and effect. Control variables must be carefully managed.
公平实验是指只有独立变量会影响因变量的实验。所有其他条件必须保持一致。这样你才能就因果关系得出有效结论。控制变量需仔细管理。
Plan your method step by step. Include all equipment, quantities and the range of independent variable values you will test. For example, if testing the effect of light intensity on plant growth, use the same type of plant, same amount of water, same soil, but vary the distance from a light source.
逐步规划你的实验方法。包括所有仪器、用量以及你要测试的独立变量取值区间。例如，测试光照强度对植物生长的影响时，采用同种植物、等量水分、相同土壤，仅改变与光源的距离。
Consider repeats: perform at least three trials for each independent variable value to identify any anomalous results and calculate a mean. This improves accuracy and reliability. Also, think about safety and obtain your teacher’s approval before starting.
考虑重复：对每个独立变量值至少进行三次试验，以识别异常结果并计算平均值。这能提高准确度和可靠性。同时，考虑安全因素，开始实验前必须得到老师的批准。
7. Recording Data: Tables | 记录数据：表格
Results should be recorded clearly in a table before you draw a graph. The first column usually shows the independent variable, and subsequent columns show the dependent variable (each repeat, then a mean column). Headings must include both the quantity and its unit, separated by a slash or in brackets, such as ‘Temperature (°C)’ or ‘Time / s’.
在绘制图表前，应将结果清晰地记录在表格中。第一列通常是独立变量，后续各列为因变量（每次重复，然后是平均值列）。表头必须包含量及其单位，用斜杠或括号分隔，如 “温度 (°C)” 或 “时间 / s”。
Here is an example of a properly formatted results table for the sugar dissolving experiment:
这是一个糖溶解实验的正确格式结果表格示例：
| Water temperature (°C) | Trial 1 (s) | Trial 2 (s) | Trial 3 (s) | Mean time (s) |
|---|---|---|---|---|
| 20 | 95 | 98 | 101 | 98 |
| 40 | 45 | 48 | 44 | 46 |
| 60 | 22 | 25 | 23 | 23 |
Make sure all entries line up correctly and use the same number of decimal places where appropriate. Draw the table with a ruler and pencil if working on paper.
确保所有数据对齐，并在适当情况下使用相同小数位数。如在纸上绘制，须用尺子和铅笔。
8. Drawing Graphs | 绘制图表
Graphs help you see patterns in results. The independent variable goes on the horizontal x-axis, and the dependent variable on the vertical y-axis. Label each axis with the variable name and unit, e.g., ‘Temperature (°C)’. Choose a suitable scale that uses at least half the graph paper and goes up in equal intervals.
图表能帮你看出结果中的规律。独立变量置于水平 x 轴，因变量置于垂直 y 轴。在每个轴上标注变量名称和单位，如 “温度 (°C)”。选择合适的标度，使其至少占据一半的坐标纸，且间距均匀。
Plot each point carefully with a small cross or dot, then draw a line of best fit, which may be a straight line or a smooth curve. Do not join point-to-point unless specifically instructed. If a point lies far off the line, circle it and label it as anomalous.
用小叉号或点仔细描点，然后画出最佳拟合线，可以是直线或光滑曲线。除非特别要求，不要逐点连线。如果某个点远离线，圈出并标注为异常值。
Give your graph a clear title, such as ‘Graph of mean time taken for sugar to dissolve against water temperature’. When describing the graph trend, use phrases like ‘as temperature increases, the time taken decreases’.
为图表写上清晰的标题，如 “糖溶解平均时间随水温变化图”。描述图表趋势时，使用类似 “随着温度升高，所需时间减少” 的表述。
9. Analysing Results and Drawing Conclusions | 分析结果与得出结论
After presenting your data, you must analyse what it shows. Look for patterns such as a linear increase, a curve, or no change. Refer directly to the numbers: ‘At 20°C the mean time was 98 s, whereas at 60°C it dropped to 23 s, showing a decrease of 75 s.’
在呈现数据后，你必须分析数据所显示的信息。寻找规律，如线性增加、曲线变化或无变化。直接引用数字：“在 20°C 时平均时间为 98 秒，而在 60°C 时降至 23 秒，减少了 75 秒。”
A conclusion should answer the original investigation question and state whether your results support a prediction. It must be backed by evidence from the data. For example: ‘The results show that as water temperature increases, the time for sugar to dissolve decreases, which supports the prediction.’
结论应回答最初的探究问题，并说明你的结果是否支持预测。结论必须有数据作为证据支撑。例如：“结果表明，随着水温升高，糖溶解时间减少，这支持了预测。”
Avoid making claims that go beyond your data. If you tested only three temperatures, you cannot say what happens at 80°C. Mention that ‘within the range tested, the pattern was…’
避免做出超出数据范围的论断。如果你只测试了三个温度，就不能说 80°C 时会怎样。应提到 “在所测试的范围内，规律是……”。
10. Evaluating Experiments and Improvements | 评估实验与改进
Evaluation is about judging the quality of your method and results. Ask yourself: Were the control variables truly kept constant? Could a measurement error have occurred? For instance, if you did not start the stopwatch and add sugar at the same instant, the time may not be accurate.
评估是评判方法与结果质量的过程。问自己：控制变量是否真正保持恒定？是否可能存在测量误差？例如，如果没有同时按下秒表和加入糖，时间就可能不准确。
Identify any anomalous results – these are points that fall well outside the general trend, such as a trial where the time was suddenly much longer. Suggest reasons: perhaps the thermometer was read incorrectly, or undissolved sugar remained. Decide whether to include them in the mean after consideration.
识别任何异常结果——即远偏离总趋势的点，例如某次试验突然用时过长。提出可能原因：温度计读数错误，或仍有未溶解的糖。在考虑后决定是否将其纳入平均值。
Propose realistic improvements. Instead of saying ‘be more careful’, suggest specific changes: ‘Use a digital thermometer for more precise temperature readings’, ‘Stir at a constant rate using a magnetic stirrer’, or ‘Increase the number of trials to five for a more reliable mean’.
提出切实可行的改进措施。不要说 “更小心些”，而应提出具体改变：“使用数字温度计以获得更精确的温度读数”，“用磁力搅拌器保持恒定搅拌速度”，或 “将试验次数增加到五次，以获得更可靠的平均值”。
Finally, comment on the overall reliability of the experiment. If repeated readings are close together, the results are reliable. If they vary widely, the method may need to be redesigned.
最后，对实验的整体可靠性进行评论。如果重复读数彼此接近，则结果可靠。如果相差很大，方法可能需要重新设计。
Published by TutorHao | Science Revision Series | aleveler.com
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