📚 Common Misconceptions in Year 7 WJEC Science and How to Correct Them | Year 7 WJEC 科学：常见误区与纠正方法
When students begin their journey in science, they bring with them everyday experiences and words that sometimes clash with scientific ideas. These clashes create misconceptions that can block deeper understanding if they are not addressed early. Year 7 is a critical time to spot and fix these mistakes, giving learners a solid foundation in biology, chemistry and physics. This article explores ten of the most common misunderstandings in the WJEC science course, explains the correct science behind each one, and offers simple ways to put things right.
当学生刚开始接触科学时，他们带着日常经验和词语，这些有时会与科学概念发生冲突。这些冲突会造成误解，如果不及时纠正，它们会阻碍更深入的理解。七年级是发现并纠正这些错误的关键时期，能为学生打下扎实的生物、化学和物理基础。本文探讨WJEC科学课程中十个最常见的误区，解释每个误区背后正确的科学知识，并提供简单方法帮助纠正。
1. Plants Get Their Food from the Soil | 植物从土壤中获取食物
A very common idea is that plants 'eat' soil, sucking up ready-made food through their roots. Many learners think that soil contains nutrients in the same way a sandwich does, and that water and minerals are the plant's main meal.
一个十分常见的想法是植物 "吃" 土壤，通过根部吸收现成的食物。许多学生认为土壤里的营养就像三明治一样，而水和矿物质是植物的主要食物。
In reality, plants make their own food by photosynthesis. Using sunlight energy, carbon dioxide from the air and water from the soil, green plants produce glucose and oxygen. The glucose is used for energy and growth, while oxygen is released. Minerals such as nitrates from the soil help build proteins, but they are not an energy source. The plant does not 'feed' on soil; it makes its own sugar inside its leaves.
事实上，植物通过光合作用自己制造食物。绿色植物利用太阳光能、空气中的二氧化碳和土壤里的水，生成葡萄糖和氧气。葡萄糖用于提供能量和生长，氧气则释放出去。土壤里的矿物质（如硝酸盐）有助于合成蛋白质，但它们并非能量来源。植物并不靠土壤 "进食"；它在叶片内部制造自己所需的糖。
To correct this, ask the question: 'If a huge tree gains most of its mass from the soil, why is there not a giant hole around its roots?' Most of the dry mass of a plant comes from carbon dioxide in the air, not from soil. Simple experiments with potted plants can show that the soil mass hardly changes while the plant grows significantly.
为了纠正这个错误，可以问一个问题："如果一棵大树的大部分重量来自土壤，为什么根周围没有一个巨大的坑？" 实际上，植物干重的大部分来自空气中的二氧化碳，而不是土壤。用盆栽植物做简单实验就可以发现，土壤质量几乎不变，而植物却长大了许多。
2. Breathing and Respiration Are the Same Thing | 呼吸和呼吸作用是一回事
Many students happily use the word 'respiration' to mean breathing in and out. They talk about 'respiring faster' when they run, meaning they are panting. This comes from everyday language where 'respiratory system' is linked only to lungs.
许多学生很自然地用 "呼吸作用" 这个词来表示吸气和呼气。他们跑步时说自己 "呼吸加快"，指的是喘气。这源于日常语言里 "呼吸系统" 只和肺联系在一起。
Scientifically, breathing (ventilation) is the movement of air into and out of the lungs. Respiration is a chemical reaction that takes place inside every living cell. It releases energy from glucose, usually using oxygen and producing carbon dioxide and water. This is why we need to breathe: to supply oxygen for respiration and remove the carbon dioxide produced.
科学上，呼吸（通风）是空气进出肺部的运动。呼吸作用则是发生在每一个活细胞内部的化学反应。它从葡萄糖中释放能量，通常需要氧气参与，并产生二氧化碳和水。这就是为什么我们需要呼吸：为呼吸作用提供氧气，并排出产生的二氧化碳。
You can think of it like a fireplace: the chimney lets air in and smoke out (breathing), while the fire itself burns fuel to release heat (respiration). Using the word 'ventilation' for breathing movements helps separate the two ideas in students' minds.
可以把它想象成一个壁炉：烟囱让空气进入并排出烟雾（呼吸），而炉火本身燃烧燃料释放热量（呼吸作用）。用 "通风" 一词描述呼吸运动，有助于在学生的头脑中把这两个概念区分开。
3. Mass and Weight Mean the Same Thing | 质量和重量是一回事
In everyday life people say 'I weigh 50 kilograms'. That sounds correct on bathroom scales, but science makes a clear distinction. The confusion is reinforced every time we talk about 'weight' when we actually mean mass.
在日常生活中，人们会说 "我体重50公斤"。这在浴室秤上听起来没错，但科学对这两者有明确区分。每当我们谈论 "重量" 实际上是指质量的时候，这种混淆就被强化了。
Mass is the amount of matter in an object. It stays the same wherever you go and is measured in kilograms (kg). Weight is the force of gravity pulling on that mass. It changes depending on the strength of gravity and is measured in newtons (N). On Earth, 1 kg of mass is pulled by gravity with a force of about 10 N. On the Moon, the mass is still 1 kg, but the weight is only about 1.6 N because gravity is weaker.
质量是物体所含物质的多少。无论你去到哪里，质量都保持不变，单位是千克（kg）。重量则是引力作用在那个质量上的力。它随引力强弱变化，单位是牛顿（N）。在地球上，1千克质量受到约10 N的引力。在月球上，质量仍然是1千克，但重量只有大约1.6 N，因为月球引力较弱。
To fix this, always use the correct units: say 'mass is 5 kg' and 'weight is 50 N'. Show that a spring balance measures weight because it stretches under a force, while a pan balance compares masses and would give the same result on the Moon and on Earth. A classroom demonstration with force meters and different gravitational field strengths helps enormously.
要纠正这一点，务必使用正确的单位：说 "质量是5千克"，"重量是50牛"。展示弹簧秤测量的是重量，因为它受力会拉伸，而托盘天平是比较质量的，在月球和地球上会给出相同结果。用测力计在不同引力场强下演示，对理解非常有帮助。
4. Electric Current Gets Used Up in a Circuit | 电流在电路中被消耗
A powerful misconception is that the battery sends out a certain amount of current, and the bulb or buzzer 'uses it up', so less current returns to the battery. Students often draw arrows on circuit diagrams that get smaller after each component.
一个很强的误区是，电池送出一定量的电流，灯泡或蜂鸣器把它 "用光了"，因此返回电池的电流变少了。学生们画电路图时常常在元件后面把箭头画小。
Current is the flow of electric charge and it is conserved around a simple series circuit. The same number of charged particles enters and leaves each component every second. What does get used up is energy. The battery transfers energy to the charges, and the bulb transforms that electrical energy into light and heat. The charges themselves are still there, carrying less energy back to the battery. It is like a water wheel in a stream: the water is not used up; it just loses some of its kinetic energy.
电流是电荷的流动，在简单串联电路中是守恒的。每秒钟进入和离开每个元件的带电粒子数量相同。真正被消耗的是能量。电池将能量传递给电荷，灯泡再将电能转化为光和热。电荷本身仍然存在，只是携带更少的能量回到电池。这就像溪流中的水车：水并没有被用光，只是损失了一部分动能而已。
A simple ammeter reading before and after a bulb will show identical values. Emphasise that the word 'current' means flow rate, not a substance that can vanish. Replacing the word 'used up' with 'energy is transferred' helps build the correct model from the start.
用电流表测量灯泡前后的电流，读数完全相同。要强调 "电流" 这个词指的是流动速率，而不是一种会消失的物质。从一开始就用 "能量被转化" 来代替 "用光"，有助于建立正确的模型。
5. Particles Themselves Expand When Heated | 加热时粒子本身会膨胀
When a metal lid gets stuck on a jar, running it under hot water helps open it. Pupils often say 'the metal expands because its particles got bigger'. They imagine the particles puffing up like tiny balloons.
当金属瓶盖卡住拧不开时，用热水冲一下就能打开。学生们经常说 "金属膨胀是因为它的粒子变大了"。他们想象粒子像小气球一样鼓起来。
Particles themselves do not change size. What increases is the space between them. Heating gives particles more kinetic energy; they vibrate or move faster and push each other further apart. This increases the volume of the material while the particles stay the same size. It is the average distance between particles that expands, not the particles themselves.
粒子本身的大小并不会改变。改变的是它们之间的间距。加热让粒子的动能增大，它们振动或运动得更快，彼此推开得更远。这使得材料的体积变大，而粒子的大小不变。膨胀的是粒子之间的平均距离，而不是粒子本身。
A useful model is a group of people standing in a crowd. If they start to dance more vigorously, they need more personal space and the crowd spreads out. The people themselves do not swell. Ball-and-ring apparatus also demonstrates this: a heated metal ball cannot pass through a ring, but when cooled it fits again, showing distance changes without particle growth.
一个有用的模型是人群。如果人们更剧烈地舞动，就需要更多个人空间，人群就会散开。人们自己并没有膨胀。球和环实验也展示了这一点：加热后的金属球穿不过圆环，冷却后又可以穿过去，说明粒子间距变了，而粒子没有长大。
6. Cold Moves into Objects | 冷会进入物体
Children often say 'close the window or the cold will get in', or 'put on a coat to stop the cold coming in'. This makes it sound as if 'cold' is a thing that flows. Even some adults talk about 'letting the cold out of the fridge'.
孩子们经常说 "关上窗户，不然冷气会进来"，或者 "穿上外套，别让寒气跑进来"。这让人觉得 "冷" 是一种可以流动的东西。甚至有些大人也说 "别让冰箱里的冷气跑出来了"。
There is no such thing as 'cold' moving. What we feel as cold is simply a lack of heat energy. Heating always causes energy to transfer from a hotter region to a colder region. When a cold object feels cold, heat is moving from your warmer hand into the colder object. The cold feeling is the loss of thermal energy from your skin.
根本不存在 "冷" 在移动这回事。我们感觉到的冷，仅仅是缺乏热能。加热总是导致能量从较热的区域传递到较冷的区域。当一个冷的物体摸起来冷时，实际上是热量从你温暖的手传到了那个较冷的物体上。冷的感觉是你的皮肤在损失热量。
Insulation does not 'trap cold'; it slows down heat transfer. A coat keeps you warm because it traps a layer of air that is a poor conductor, reducing heat loss from your body. Discussing heat always as something that can be transferred, and 'cold' as the relative absence of heat, builds a better physical understanding.
保温材料并不会 "锁住冷气"，而是减缓热量传递。外套让你暖和是因为它锁住了一层不良导体的空气，降低了身体热量的散失。始终把热视为可传递的东西，而 "冷" 表现为热量的相对缺失，能帮助学生建立更好的物理理解。
7. All Acids Are Strong and Dangerous | 所有酸都是强酸而且危险
When students first hear 'acid', they picture a bubbling, corrosive liquid that eats through metal and skin. The word carries a scary meaning, so they imagine that lemon juice and vinegar must be just as harmful as laboratory acids, only 'weaker' in the sense of being diluted with water.
当学生第一次听到 "酸" 时，脑海中就会出现冒泡的腐蚀性液体，会腐蚀金属和皮肤。这个词带有危险的含义，因此他们想象柠檬汁和醋一定和实验室里的酸一样有害，只是被水稀释了而已。
There is a difference between 'strong' and 'concentrated'. A strong acid is one that completely splits up into ions in water, like hydrochloric acid. A weak acid, such as ethanoic acid in vinegar, only partly splits up. However, a weak acid can be concentrated if it has little water. Strong and weak refer to the degree of ionisation, not how dangerous something is. Many weak acids are found in everyday foods and are perfectly safe in small amounts.
"强" 和 "浓" 是有区别的。强酸是在水中完全电离的酸，比如盐酸。弱酸，比如醋里的乙酸，只是部分电离。但弱酸如果水很少，也可以很浓。强和弱指的是电离程度，并不是指危险程度。许多弱酸存在于日常食物中，少量食用是完全安全的。
Compare laboratory hydrochloric acid (strong and often dilute) with vinegar (weak but concentrated). Use pH paper and conductivity tests: a strong acid at low concentration still conducts electricity well, while a weak acid at the same concentration conducts poorly. Letting students handle safe weak acids like citric acid removes unnecessary fear.
比较实验室里的盐酸（强，但往往是稀溶液）和醋（弱，但可能是浓溶液）。用pH试纸和导电性测试：低浓度的强酸导电性依然很好，而同样浓度的弱酸导电性就差。让学生亲手接触安全的弱酸（如柠檬酸），可以消除不必要的恐惧。
8. The Sun Is a Burning Ball of Fire | 太阳是一个燃烧的火球
Children grow up drawing the Sun as a yellow circle with orange flames. When asked what makes the Sun shine, a frequent answer is 'it's a huge ball of fire, like a campfire but bigger'. They picture a chemical combustion reaction, needing fuel and oxygen.
孩子们从小就画太阳：一个黄色圆盘带着橙色火焰。当问到太阳为什么发光时，常见的回答是 "它是一个巨大的火球，就像篝火，只是更大"。他们想象的是需要燃料和氧气的化学燃烧反应。
The Sun does not burn in the chemical sense. It is powered by nuclear fusion. In the Sun' to a huge amount of energy, following the equation E=mc². There is no oxygen involved and no 'flame' as we know it. The glowing surface is a super-hot plasma, not a fire.
太阳并不是化学意义上的燃烧。它的能量来自核聚变。在太阳核心，氢原子核在极高的压力和温度下被迫结合成氦。这个过程将少量质量转化为巨大的能量，遵循公式E=mc²。这个过程不需要氧气，也没有我们通常理解的"火焰"。发光的表面是超高温的等离子体，不是火。
To correct this, contrast a candle flame (chemical reaction with oxygen, produces carbon dioxide and soot) with the Sun (nuclear reaction). You can use simple modelling with two magnets forced together to represent fusion, releasing energy. Emphasise that the Sun has no oxygen tanks—it is mostly hydrogen and helium.
为纠正这一点，可以将蜡烛火焰（与氧气发生化学反应，产生二氧化碳和烟灰）与太阳（核反应）进行对比。可以用两块磁铁强行压在一起代表聚变并释放能量来简单模拟。要强调太阳并没有氧气罐——它主要由氢和氦组成。
9. Solids Melt Because the Particles Break Apart | 固体熔化是因为粒子裂开了
When ice melts into water, some students think the solid water particles 'break' or 'shatter' into smaller pieces. They may say the particles themselves turn into liquid particles, as if the particles are physically smashed during melting.
当冰融化成水时，有些学生认为固态的水粒子 "碎裂" 或 "破碎" 成更小的碎片了。他们可能会说粒子本身就化成了液体粒子，好像粒子在熔化过程中被物理打碎了一样。
Melting is not about breaking particles, but about weakening the forces between them. In a solid, particles are held tightly in fixed positions by strong attractive forces; they vibrate but cannot move around. When heated, the particles gain energy and vibrate more vigorously until the forces can no longer hold them in fixed positions. They then slide past each other as a liquid, but the particles themselves remain whole. There is no chemical change and the particles are exactly the same size and type.
熔化并不是粒子碎裂，而是粒子间的吸引力减弱了。在固体中，粒子被强大的吸引力牢牢固定在位置上，它们振动但不能自由移动。加热时，粒子获得能量，振动更加剧烈，直到吸引力无法再把它们束缚在固定位置上。它们随后像液体一样滑过彼此，但粒子本身保持完整。没有发生化学变化，粒子的大小和种类都完全不变。
Demonstrate this with ball bearings on a vibrating tray: a gentle shake keeps them in a fixed pattern (solid model), while a stronger shake allows them to roll around (liquid model). The ball bearings do not break. Similarly, melting butter or chocolate can be reversed by cooling, showing particles are unchanged.
可以用振动的托盘上的滚珠演示：轻微振动让它们保持固定排列（固体模型），较强振动则让它们滚动起来（液体模型）。滚珠并没有碎裂。同样，融化黄油或巧克力再冷却后可以复原，说明粒子并未改变。
10. Food Is 'Burned' Inside the Body by Digestion | 食物在体内是通过消化 "燃烧" 的
Year 7 pupils often think that digestion is how the body extracts energy from food, sometimes comparing the stomach to a furnace that burns the meal. They mix up the jobs of the digestive system and the respiratory system.
七年级学生常常认为消化是身体从食物中提取能量的方式，有时把胃比作焚烧食物的炉子。他们混淆了消化系统和呼吸作用系统的功能。
Digestion is the breakdown of large, insoluble food molecules into small, soluble ones that can pass into the blood. It is a chemical process involving enzymes, but it does not release usable energy for the body in the way respiration does. The energy in food is locked in chemical bonds and is only released later inside cells through respiration, which requires oxygen. The digestive system prepares the fuel; the cells burn it.
消化是指大的、不溶的食物分子分解为小的、可溶的分子，从而可以进入血液。这是一个涉及酶的化学过程，但它并不像呼吸作用那样为身体直接释放可用的能量。食物中的能量储存在化学键里，只在后续细胞内的呼吸作用中才被释放，并且需要氧气。消化系统准备好燃料，细胞再把它 "燃烧" 掉。
To clarify, use a 'fuel delivery' analogy: a tanker delivers petrol (digestion bringing glucose into blood), but the car's engine actually burns the petrol to move the car (respiration in cells). Show that undigested food still contains energy, but it cannot be used by the body until it crosses the gut wall and reaches the cells.
为了解释清楚，可以用 "燃料运输" 做类比：油罐车运送汽油（消化把葡萄糖送入血液），但汽车的发动机才真正燃烧汽油驱动汽车（细胞内的呼吸作用）。展示未经消化的食物仍然含有能量，但在穿过肠壁并到达细胞之前，身体无法使用这些能量。
Published by TutorHao | Science Revision Series | aleveler.com
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