📚 Year 8 WJEC Science: Core Knowledge Checklist | Year 8 WJEC 科学：核心知识点梳理
Year 8 Science in the WJEC curriculum builds on KS3 foundations and prepares students for the depth of GCSE topics. This article provides a clear, structured checklist of the essential concepts you need to master—from cells and particles to forces and ecosystems. Use it to revise key ideas and check your understanding.
在 WJEC 课程体系中，Year 8 科学在 KS3 基础上进一步深化，为 GCSE 主题奠定基础。本文提供了一个清晰、结构化的核心概念清单，涵盖从细胞与粒子到力与生态系统等必备知识。用它来复习重点并检查理解程度。
1. Cells and Organisation | 细胞与组织
All living organisms are made of cells. Animal cells typically contain a nucleus, cytoplasm, cell membrane and mitochondria. Plant cells have the same basic parts but also a rigid cell wall, a large permanent vacuole and chloroplasts for photosynthesis.
所有生物体都由细胞构成。动物细胞通常包含细胞核、细胞质、细胞膜和线粒体。植物细胞除了这些基本结构外，还有坚硬的细胞壁、一个大的中央液泡以及用于光合作用的叶绿体。
Cells are organised into tissues, such as muscle tissue or xylem. Tissues work together to form organs like the heart or leaf. Organs form organ systems, such as the digestive system, which allows complex organisms to function efficiently.
细胞组织成组织，例如肌肉组织或木质部。组织共同构成器官，如心脏或叶。器官又组成器官系统，例如消化系统，这让复杂的生物体能够高效运转。
2. Particle Model and States of Matter | 粒子模型与物质状态
According to the particle model, all matter consists of tiny particles that are constantly moving. In solids, particles are tightly packed in a regular pattern and only vibrate. In liquids, particles are close together but can move past each other. In gases, particles are far apart and move rapidly in all directions.
根据粒子模型，所有物质都由不断运动的微小粒子组成。在固体中，粒子紧密排列成规则结构，只能振动。在液体中，粒子彼此靠近但能相对滑动。在气体中，粒子相距很远，朝各个方向快速运动。
Changes of state, such as melting, freezing, boiling and condensing, can be explained by the gain or loss of energy. Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
物质状态的变化，如熔化、凝固、沸腾和冷凝，可以用能量得失来解释。扩散是粒子从高浓度区域向低浓度区域的运动。
3. Atoms, Elements and Compounds | 原子、元素和化合物
An atom is the smallest unit of an element that retains its chemical properties. Atoms contain protons (+), neutrons (0) and electrons (−). The nucleus is made of protons and neutrons, while electrons orbit in shells.
原子是保持元素化学性质的最小单位。原子包含质子（正电）、中子（不带电）和电子（负电）。原子核由质子和中子构成，电子则在电子层上绕核运动。
Elements are pure substances made of only one type of atom, shown by chemical symbols. Compounds form when two or more elements chemically combine in fixed proportions, represented by chemical formulas such as H₂O or CO₂.
元素是只由一种原子组成的纯净物，用化学符号表示。当两种或多种元素以固定比例化学结合时，就形成化合物，用化学式表示，例如 H₂O 或 CO₂。
4. Chemical Reactions and Equations | 化学反应与方程式
Chemical reactions involve the formation of new substances. Signs include colour change, gas production, temperature change or formation of a precipitate. The original substances are reactants; what is produced are products.
化学反应涉及生成新物质。迹象包括颜色变化、产生气体、温度变化或生成沉淀。起始物质是反应物，生成的物质是产物。
The law of conservation of mass states that the total mass of reactants equals the total mass of products. Word equations and symbol equations must be balanced to show this conservation.
magnesium + oxygen → magnesium oxide
质量守恒定律指出，反应物的总质量等于生成物的总质量。文字方程式和符号方程式必须配平以体现守恒。例如：镁 + 氧气 → 氧化镁。
5. Acids and Alkalis | 酸与碱
The pH scale ranges from 0 to 14. Acids have a pH less than 7, alkalis have a pH greater than 7, and a pH of 7 is neutral. Universal indicator turns red in strong acids, green in neutral, and purple in strong alkalis.
pH 标度范围从 0 到 14。酸性的 pH 小于 7，碱性的 pH 大于 7，pH 为 7 是中性。通用指示剂在强酸中变红，中性变绿，强碱中变紫。
ide + water. This is an important reaction in everyday life, such as treating indigestion.
在中和反应中，酸和碱反应生成盐和水。例如：盐酸 + 氢氧化钠 → 氯化钠 + 水。这是日常生活中的重要反应，例如治疗胃灼热。
6. Forces and Motion | 力与运动
Forces are pushes or pulls measured in newtons (N). Common forces include gravity, friction, air resistance and upthrust. When forces on an object are balanced, its speed and direction stay constant. Unbalanced forces cause acceleration or deceleration.
力是推或拉，单位为牛顿（N）。常见的力包括重力、摩擦力、空气阻力和浮力。当物体受到平衡力作用时，其速度和方向保持不变。不平衡力则导致加速或减速。
speed = distance ÷ time
速度计算公式：速度 = 距离 ÷ 时间。距离–时间图显示物体随时间移动的距离；水平直线表示静止，斜率越大表示速度越快。
7. Energy Transfers and Stores | 能量传递与储存
Energy exists in different stores: kinetic, thermal, chemical, gravitational potential, elastic potential, and nuclear. Energy can be transferred from one store to another by heating, by doing work, or by radiation.
能量以不同的形式储存：动能、热能、化学能、重力势能、弹性势能和核能。能量可以通过加热、做功或辐射等方式从一种储存形式传递到另一种。
The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed. Useful energy transfers often produce wasted energy, usually as heat, which spreads out and becomes less useful.
能量守恒定律指出，能量既不能被创造也不能被消灭，只能被传递或转化。有用的能量传递通常会产生浪费的能量，通常以热的形式散失并变得较不易利用。
8. Electricity and Circuits | 电与电路
An electric current is a flow of electric charge, measured in amperes (A). Voltage (potential difference) is the push that drives the current, measured in volts (V). Resistance opposes the flow, measured in ohms (Ω).
电流是电荷的流动，单位为安培（A）。电压（电势差）是推动电流的动力，单位为伏特（V）。电阻阻碍电流，单位为欧姆（Ω）。
Circuit diagrams use standard symbols for components such as cells, switches, lamps and resistors. In a series circuit, the current is the same everywhere, while in a parallel circuit the current splits between branches.
电路图使用标准符号来表示元件，如电池、开关、灯泡和电阻器。在串联电路中，各处电流相同；在并联电路中，电流在各支路之间分配。
9. Reproduction and Growth | 生殖与生长
In humans, reproduction involves the male and female reproductive systems. Sperm are produced in the testes and eggs in the ovaries. Fertilisation occurs when a sperm cell fuses with an egg cell in the fallopian tube.
人类的生殖涉及男性和女性生殖系统。精子在睾丸中产生，卵子在卵巢中产生。当精子和卵子在输卵管中融合时就发生了受精。
Puberty brings physical changes driven by hormones, including growth spurts and development of secondary sexual characteristics. The menstrual cycle prepares the female body for possible pregnancy each month.
青春期在激素作用下带来身体变化，包括生长突增和第二性征的发育。月经周期每月为可能的怀孕做准备。
10. Ecosystems and Interdependence | 生态系统与相互依存
An ecosystem consists of a community of organisms interacting with their physical environment. Producers (e.g., plants) make their own food through photosynthesis. Consumers eat other organisms, and decomposers break down dead matter.
生态系统由生物群落与其物理环境相互作用组成。生产者（例如植物）通过光合作用制造自身食物。消费者以其他生物为食，分解者分解死物。
Food chains and food webs show feeding relationships. The populations of predators and prey are interlinked; a change in one population affects the other. Interdependence means that all species in an ecosystem rely on each other for survival.
食物链和食物网展示了摄食关系。捕食者与猎物的种群相互关联；一个种群的变化会影响另一个。相互依存意味着生态系统中所有物种互相依赖以求生存。
11. The Solar System and Beyond | 太阳系及外太空
Our Solar System consists of the Sun, eight planets, dwarf planets, moons, asteroids and comets. The planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Gravity keeps planets in orbit.
我们的太阳系由太阳、八大行星、矮行星、卫星、小行星和彗星组成。从太阳向外行星依次为水星、金星、地球、火星、木星、土星、天王星和海王星。引力使行星保持在轨道上。
Earth rotates on its axis once every 24 hours, causing day and night. It takes 365¼ days to orbit the Sun, and its tilted axis produces the seasons. The geocentric model was replaced by the heliocentric model thanks to scientists like Galileo.
地球每 24 小时自转一周，产生了昼夜。它围绕太阳公转一周需要 365¼ 天，其倾斜的地轴产生了季节。得益于伽利略等科学家，地心说被日心说所取代。
12. Separating Mixtures | 混合物分离
Mixtures contain two or more substances that are not chemically combined and can be separated by physical methods. Filtration separates an insoluble solid from a liquid. Evaporation can obtain a soluble solid from a solution.
混合物含有两种或多种未化学结合的物质，可以用物理方法分离。过滤可将不溶性固体从液体中分离出来。蒸发可从溶液中获得可溶性固体。
Distillation is used to separate a liquid from a solution based on differences
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