📚 Key Practical Skills for Year 7 Biology | 七年级生物实验技能要点
Practical work is at the heart of biology. In Year 7 WJEC science, you will learn how to use equipment safely, make observations, collect accurate data, and analyse your results. Mastering these practical skills will not only earn you marks in assessments but also build your confidence as a young scientist. This guide covers the key points you need to remember for your practical tests and experiments, from setting up a microscope to drawing graphs and writing conclusions.
实验操作是生物学的核心。在七年级 WJEC 科学课中，你将学习如何安全使用器材、进行观察、收集准确数据并分析结果。掌握这些实践技能不仅能帮你在考核中取得好分数，还能建立你作为小科学家的信心。本指南涵盖了你需要在实验测试和操作中记住的关键要点，从显微镜的调试到绘制图表、撰写结论。
1. Safety First | 安全第一
Always wear safety goggles and a lab coat to protect your eyes and clothing from chemicals or flames. Even if you are not handling dangerous substances, glassware can break unexpectedly.
始终佩戴护目镜和实验服，以保护眼睛和衣物免受化学品或火焰伤害。即使你没有接触危险物质，玻璃器皿也可能意外破裂。
Long hair must be tied back, and any loose jewellery should be removed before you start an experiment. This stops hair catching fire on a Bunsen burner and prevents jewellery from dipping into chemicals.
长发必须束起，实验前应取下所有松散的首饰。这样可以避免头发被本生灯点燃，也防止首饰浸入化学品中。
Never taste or directly smell any chemical. If you need to smell a substance, use the wafting technique: gently wave your hand over the container towards your nose. Always tell your teacher immediately if anything spills or breaks.
切勿品尝或直接闻任何化学品。如果需要闻气味，请使用扇闻法：用手轻轻将容器口的气体扇向鼻子。若有任何溢出或破损，立即报告老师。
Know the location of the fire extinguisher, fire blanket and eye wash station before you begin. A simple rule is: stay calm, don't run, and follow your teacher's instructions.
实验前要清楚灭火器、灭火毯和洗眼器的位置。一条简单的规则是：保持冷静，不要奔跑，听从老师的指示。
2. Using a Light Microscope | 使用光学显微镜
Always carry the microscope with two hands, one holding the arm and the other supporting the base. Place it on a flat bench, away from the edge.
搬动显微镜时始终用双手，一手握住镜臂，一手托住底座。将其放置在平坦的实验台上，远离边缘。
Use the coarse focus knob to raise the stage until it is close to the lens, but look from the side to prevent the lens from hitting the slide.
先用最低倍物镜（通常是 ×4 或 ×5）对光。使用粗准焦螺旋使载物台上升，直到接近镜头，但从侧面观察以避免镜头撞击玻片。
Look through the eyepiece and slowly lower the stage with the coarse focus until the image appears roughly clear. Then use the fine focus knob to get a sharp image. If you need higher magnification, switch to a higher power objective, but only use the fine focus after that.
通过目镜观察，用粗准焦螺旋慢慢降低载物台，直到图像大致清晰。然后用细准焦螺旋调出清晰画面。如需更高倍率，换用高倍物镜，但之后只能使用细准焦螺旋调焦。
Adjust the diaphragm or mirror to let enough light through. On a light microscope, a larger opening lets in more light, which can be useful for thicker specimens.
调节光圈或反光镜让充足光线通过。在光学显微镜中，较大的光圈可让更多光线进入，对较厚标本有利。
3. Making a Wet Mount Slide | 制作临时装片
To prepare a temporary slide, place a drop of water in the centre of a clean glass slide using a dropping pipette. If you are studying cells, you might use a stain like iodine or methylene blue instead of water to make cell parts more visible.
制作临时装片时，用滴管在洁净载玻片中央滴一滴水。如果你在观察细胞，可以用碘液或亚甲蓝等染色剂代替水，使细胞结构更清晰可见。
Place your specimen, such as a thin layer of onion epidermis or a strand of pond weed, into the drop of liquid. Lower a cover slip at a 45-degree angle onto the slide using a mounted needle; this reduces air bubbles.
将标本（如一层薄洋葱表皮或一条水绵）放入液滴中。用解剖针以 45 度角轻轻放下盖玻片，这能减少气泡的产生。
If too much liquid spills out, blot it carefully with a piece of filter paper. The slide is now ready to place on the microscope stage. Always ensure the slide is labelled and clean.
如果液体溢出过多，用滤纸小心吸干。装片现在就能放到显微镜载物台上了。务必保证玻片清洁并做好标记。
4. Drawing Scientific Diagrams | 绘制科学图
In practical assessments, you will often be asked to draw what you see under the microscope. Use a sharp pencil and draw clean, continuous outlines. Do not sketch or shade; biological drawings should use clear lines only.
在实践考核中，你常被要求画出显微镜下所见。使用削尖的铅笔，画出干净、连续的轮廓。不要素描或涂阴影；生物图只能用清晰的线条绘制。
Always add a title that says what the drawing shows, e.g., 'Drawing of an onion epidermal cell'. Label the structures with straight ruler lines, not arrowheads. Write labels horizontally and to the right of the diagram if possible.
总要加上标题说明所画内容，例如“洋葱表皮细胞图”。用直尺画线标注结构，不要使用箭头。标签应水平书写，尽可能写在图的右侧。
. Note the magnification used, calculated as eyepiece magnification × objective magnification.
如果细胞很多，不需要画出每一个。只需画出几个有代表性的细胞，正确表现其排列方式和比例。记录所用的放大倍数，即目镜倍数 × 物镜倍数。
5. Variables: Independent, Dependent and Control | 变量：自变量、因变量和控制变量
Understanding variables is crucial for planning experiments. The independent variable is the one you change deliberately (e.g., the temperature of water). The dependent variable is the one you measure or observe (e.g., how many bubbles a pondweed produces).
理解变量对设计实验至关重要。自变量是你有意改变的变量（例如水温）。因变量是你测量或观察的变量（例如水绵产生的气泡数量）。
Control variables are all the factors you must keep the same to make the test fair, such as light intensity, volume of water, and the type of plant. If you don't control these, you cannot be sure that changes in the dependent variable were caused by the independent variable.
控制变量是你必须保持相同的所有因素，比如光照强度、水量和植物种类，以保证测试公平。若不控制这些，你就无法确定因变量的变化是否由自变量引起。
In an assessment, always identify the three types of variable before starting. A good way to remember is: 'I change' (independent), 'I measure' (dependent), 'I keep the same' (control).
在考核中，开始前始终要识别这三类变量。一个记住它们的好方法是：“我改变”（自变量）、“我测量”（因变量）、“我保持不变”（控制变量）。
6. Planning a Fair Test | 设计公平测试
A fair test is an experiment where only one independent variable is altered, and all control variables are kept constant. This ensures that the results are reliable. You should also consider using a control group where appropriate, such as a tube with water but no enzyme to compare with the reaction tubes.
公平测试是指实验中只改变一个自变量，而所有控制变量保持不变。这样才能保证结果可靠。你还应考虑在适合时使用对照组，比如设置一个只含水不含酶的试管，与反应管进行对比。
Before you start, write a step-by-step method. Be specific about quantities ('5 cm³ of starch solution'), times ('count bubbles for 1 minute'), and repeat measurements ('repeat 3 times and calculate a mean'). This helps others reproduce your experiment.
开始之前，写出分步方法。要明确用量（“5 厘米³ 淀粉溶液”）、时间（“计数气泡 1 分钟”）和重复测量（“重复 3 次并计算平均值”）。这有助于他人重现你的实验。
Risk assessment is also part of planning. Identify possible hazards (e.g., hot water, sharp scissors) and explain how you will reduce the risk (e.g., use tongs, wear gloves). This shows you are a responsible scientist.
风险评估也是计划的一部分。识别可能的危险（如热水、锋利的剪刀）并解释你将如何降低风险（如使用坩埚钳、佩戴手套）。这表明你是一名负责任的科学家。
7. Measuring Accurately | 准确测量
Choose the right instrument for the job. For small volumes of liquid, use a graduated syringe or a measuring cylinder with a fine scale. Read the bottom of the meniscus at eye level to avoid parallax error.
选择合适的测量仪器。对于少量液体，使用带刻度的注射器或精细刻度的量筒。在视线水平处读取凹液面底部，以避免视差错误。
When measuring temperature, keep the thermometer bulb fully immersed but not touching the container's bottom. Wait for the reading to stabilise before recording it. Thermometers usually mark every 1 °C, so you can estimate to the nearest 0.5 °C.
测量温度时，将温度计球泡完全浸入液体但不要碰到容器底部。等待读数稳定后再记录。温度计通常以 1 °C 为分度，因此你可以估读到最接近的 0.5 °C。
For time, use a stopwatch and record in seconds or minutes as appropriate. Always note the units you used. In tables, write the unit in the header, not after every number, e.g., 'Time (s)'.
对于时间，使用秒表并视情况以秒或分钟记录。始终注明所用单位。在表格里，将单位写在表头，而非每个数字后面，如“时间 (s)”。
8. Recording Data in Tables | 用表格记录数据
All practical work requires clear data recording. Draw a table before you start collecting results. The table should have ruled columns and rows, with the independent variable in the first column and the dependent variable in the next columns.
所有实验工作都需要清晰的数据记录。在收集结果之前先画好表格。表格应有直线分隔的行列，自变量放在第一列，因变量放在后续列中。
Column headings must include the quantity and the unit, for example, 'Length of potato chip (mm)' or 'Volume of gas produced (cm³)'. Do not write units inside the data cells. Record raw data exactly as you observe it, even if it seems odd.
列标题必须包含数量和单位，例如“薯条长度 (mm)”或“产生气体的体积 (cm³)”。不要在数据单元格内写单位。按你所观察到的如实记录原始数据，即使它看起来奇怪。
If you take repeated readings, include a column for each repeat and a final column for the mean (average). Calculate the mean by adding the values and dividing by the number of values, ignoring any anomalous results.
如果你进行了重复读数，为每次重复设置一列，最后一列放平均值。平均值通过将数值相加再除以数值个数来计算，忽略任何异常结果。
9. Drawing Graphs | 绘制图表
Choose the correct graph type for your data. Use a bar chart when one variable is categoric (e.g., different types of food) and a line graph when both variables are continuous (e.g., temperature over time). In Year 7, you will mostly use bar charts and simple line graphs.
为你的数据选择合适的图表类型。当一个变量是类别变量时（如不同种类的食物），使用条形图；当两个变量都是连续变量时（如温度随时间变化），使用折线图。在七年级，你主要会用到条形图和简单折线图。
Plot the independent variable on the x-axis (horizontal) and the dependent variable on the y-axis (vertical). Label each axis with the variable and its unit, and use a sensible scale that uses at least half of the grid area. Points should be marked with small, sharp crosses.
将自变量标在 x 轴（横向），因变量标在 y 轴（纵向）。每个轴都要标记变量及其单位，并选用一个合理的刻度，使图形至少占据网格区域的一半。数据点应用锋利的细十字标记。
For line graphs, either draw a smooth curve of best fit or join points with straight lines, depending on your teacher's instruction. For bar charts, make bars of equal width with clear gaps between them. Always give the graph a descriptive title.
对于折线图，根据老师要求，要么画一条平滑的最佳拟合曲线，要么用直线逐点连接。对于条形图，要画等宽的长条并且条间留有清晰间隙。始终给图表加上描述性标题。
10. Identifying Patterns and Anomalies | 识别规律与异常值
Once you have a graph or table, look for patterns. Does the dependent variable increase as the independent variable increases? Does it decrease, or stay the same? Describe the trend in words, e.g., 'As temperature increased, the number of oxygen bubbles produced by the pondweed increased up to 30 °C, then decreased.'
当你有了图表或表格后，寻找规律。因变量是否随自变量增加而增加？是减少还是保持不变？用语言描述趋势，例如：“随着温度升高，水绵产生的氧气泡数量增加至 30 °C，然后减少。”
An anomalous result is a reading that does not fit the overall pattern. On a graph, it sits far away from the line of best fit. If you see an anomaly, check if you misread the equipment or made a mistake in recording. You can repeat the measurement to confirm.
异常值是不符合整体规律的读数。在图表中，它远离最佳拟合线。如果发现异常值，检查是否读错仪器或记录错误。可重复测量以确认。
When calculating a mean, it is acceptable to leave out an anomalous result, but you must state that you have done so and suggest a reason. This shows you can think critically about data.
计算平均值时，可以剔除异常值，但你必须说明这一点并给出理由。这表明你能批判性地思考数据。
11. Evaluating Your Experiment | 评价你的实验
Evaluation means looking back at your method and results honestly. Ask yourself: Were my measurements precise and accurate? Precision means getting similar readings each time; accuracy means being close to the true value.
评价意味着诚实地回顾你的方法和结果。问自己：我的测量精确且准确吗？精确是指每次读数相似；准确是指接近真实值。
Identify any sources of error. Systematic errors (such as a poorly calibrated thermometer) affect all results in the same way. Random errors (such as human reaction time when starting a stopwatch) cause variation in both directions. Identify which type might have affected your experiment.
识别任何误差来源。系统误差（如校准不良的温度计）会以相同方式影响所有结果。随机误差（如按下秒表时的人为反应时间）会导致双向变化。指出可能影响实验的误差类型。
Suggest improvements. For example, 'Using a water bath to maintain a constant temperature would reduce temperature fluctuations.' Even if your results are good, there is always room for improvement, and examiners look for this reflection.
提出改进建议。例如，“使用水浴来保持恒温可以减少温度波动。”即使你的结果很好，也总有改进空间，考官会看重这种反思。
12. Writing a Conclusion | 撰写结论
Your conclusion should directly answer the aim or research question. Start by summarising the trend you observed. State whether your results support your hypothesis or not, referring to the data.
你的结论应该直接回答实验目的或研究问题。首先总结你观察到的趋势。说明你的结果是否支持你的假设，并引用数据。
For example, 'The results show that higher light intensity up to 2000 lux increased the rate of photosynthesis in pondweed, as the mean number of bubbles rose from 3 to 12 per minute. This supports the prediction that light affects photosynthesis rate.'
例如，“结果表明，在 2000 勒克斯以下，光强度越高，水绵的光合作用速率越快，平均气泡数从每分钟 3 个增加到 12 个。这支持了光影响光合速率的预测。”
Do not introduce new information. Only comment on what you actually observed and measured. If your pattern was not as expected, do not adjust data to fit. Instead, explain possible reasons in the evaluation section.
不要引入新信息。只评论你实际观察和测量的内容。如果规律与预期不符，不要调整数据去迎合。相反，在评价部分解释可能的原因。
A good conclusion in Year 7 should be short, clear, and linked to the evidence. It does not need complicated statistical language, but it must show you understood the practical work you carried out.
七年级的出色结论应简短、清晰，并与证据相关联。它不需要复杂的统计语言，但必须表明你理解了自己所做的实验操作。
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