What your child learns in Key Stage 3 science

Cells and organisation

• Cells as the fundamental unit of living organisms, including how to observe, interpret and record cell structure using a light microscope
• The functions of the cell wall, cell membrane, cytoplasm, nucleus, vacuole, mitochondria and choroplasts
• The similarities and differences between plant and animal cells
• The role of diffusion in the movement of materials in and between cells
• The structural adaptations of some unicellular organisms
• The hierarchical organisation of multicellular organisms: from cells to tissues to organs to systems to organisms.

The particulate nature of matter

• The properties of the different states of matter (solid, liquid, gas) in terms of the particle model, including gas pressure
• Changes of state in terms of the particle model.

Atoms, elements and compounds

• A simple (Dalton) atomic model
• Differences between atoms, elements and compounds
• Chemical symbols and formulae for elements and compounds
• Conservation of mass changes of state and chemical reactions.

Pure and impure substances

• The concept of a pure substance
• Mixtures, including dissolving
• Diffusion in terms of the particle model
• Simple techniques for separating mixtures: filtration, evaporation, distillation and chromatography
• The identification of pure substances.

Chemical reactions

• Chemical reactions as the rearrangement of atoms
• Representing chemical reactions using formulae and equations
• Combustion, thermal decomposition, oxidation and displacement reactions
• Defining acids and alkalis in terms of neutralisation reactions
• The pH scale for measuring acidity and alkalinity, and indicators
• Reactions of metals with acids to produce a salt plus hydrogen
• Reactions of acids with alkalis to produce a salt plus water
• What catalysts do.

Energetics

• Energy changes on changes of state (qualitative)
• Exothermic and endothermic chemical reactions (qualitative).

The Periodic Table

• The varying chemical and physical properties of different elements
• The principles underpinning the Mendeleev Periodic Table
• The Periodic Table: periods and groups; metals and non-metals
• How patterns in reactions can be predicted with reference to the Periodic Table
• The properties of metals and non-metals
• The chemical properties of metal and non-metal oxides with respect to acidity. 

Materials

• The order of metals and carbon in the reactivity series
• The use of carbon in obtaining metals from metal oxides
• Properties of ceramics, polymers and composites (qualitative).

Earth and atmosphere

• The composition of the Earth
• The structure of the Earth
• The rock cycle and formation of igneous, sedimentary and metamorphic rocks
• Earth as a source of limited resources and the efficacy of recycling
• The carbon cycle
• The composition of the atmosphere
• The production of carbon dioxide by human activity and the impact on climate.

Calculation of fuel uses and costs in the domestic context

• Comparing energy values of different foods in kJ (from labels)
• Comparing power ratings of appliances in Watts (W and kW)
• Comparing amounts of energy transferred (J, kJ, kW hour)
• Domestic fuel bills, fuel use and costs
• Fuels and energy resources.

Energy changes and transfers

• Simple machines give bigger force but at the expense of smaller movement (and vice versa): product of force and displacement unchanged
• Heating and thermal equilibrium: temperature difference between two objects leading to energy transfer from the hotter to the cooler one, through contact (conduction) or radiation; such transfers tending to reduce the temperature difference; use of insulators
• Other processes that involve energy transfer: changing motion, dropping an object, completing an electrical circuit, stretching a spring, metabolism of food, burning fuels.

Changes in systems

• Energy as a quantity that can be quantified and calculated; the total energy has the same value before and after a change
• Comparing the starting with the final conditions of a system and describing increases and decreases in the amounts of energy associated with movements, temperatures, changes in position in a field, in elastic distortions and in chemical compositions
• Using physical processes and mechanisms, rather than energy, to explain the intermediate steps that bring about such changes.

Describing motion

• Speed and the quantitative relationship between average speed, distance and time (speed = distance / time)
• The representation of a journey on a distance-time graph
• Relative motion: trains and cars passing each other.

Forces

• Forces as pushes or pulls, arising from the interaction between two objects
• Using force arrows in diagrams, adding forces in one dimension, balanced and unbalanced forces
• Moment as the turning effect of a force
• Forces associated with deforming objects: stretching and squashing (springs), rubbing and friction between surfaces, pushing things out of the way, resistance to motion of air and water
• Forces measured in newtons, measurements of stretch or compression as force is changed
• Force-extension linear relation: Hooke's law as a special case
• Work done and energy changes on deformation
• Non-contact forces: gravity forces acting at a distance on Earth and in space, forces between magnets and forces due to static electricity.

Pressure in fluids

• Atmospheric pressure, decreases with increase of height as weight of air above decreases with height
• Pressure in liquids, increasing with depth: upthrust effects, floating and sinking
• Pressure measured by ratio of force over area.

Balanced forces

• Opposing forces and equilibrium: weight held by stretched spring or supported on a compressed surface.

Forces and motion

• Forces being needed to cause objects to start or stop moving, or to change their speed or direction of motion 
• Change depending on direction of force and its size.

Observed waves

• Waves on water as undulations which travel through water with transverse motion; these waves can be reflected, and add or cancel - superposition.

Sound waves

• Frequencies of sound waves, measured in hertz (Hz); echoes, reflection and absorption of sound
• Sound needs a medium to travel: the speed of sound in air, water and solids
• Sound produced by vibration of objects, in loud speakers, detected by their effects on microphone diaphragm and the ear drum
• Auditory range of humans and animals.

Energy and waves

• Pressure waves transferring energy; use for cleaning and physiotherapy by ultrasound; waves transferring information for conversion to electrical signals by microphone.

Light waves

• The similarities and differences between light waves and waves in matter
• Light waves travelling through a vacuum; the speed of light
• The transmission of light through materials: absorption, diffuse scattering and specular reflection at a surface.
• Use of ray model to explain imaging in mirrors, the pinhole camera, the refraction of light and action of convex lens in focusing, the human eye
• Light transferring energy from source to absorber leading to chemical and electrical effects; photosensitive material in the retina and in cameras
• Colours and the different frequencies of light, white light and prisms, differential colour effects in absorption and diffuse reflection. 

Current electricity

• Electric current, measured in amperes: in circuits (series and parallel), currents add where branches meet, and current as flow of charge
• Potential difference, measured in volts, battery and bulb ratings; resistance, measured in ohms, as the ratio of potential difference to current
• Differences in resistance between conducting and insulating components.

Static electricity

• Separation of positive or negative charges when objects are rubbed together: transfer of electrons, forces between charged objects
• The idea of electric field: forces acting across the space between objects not in contact.

Magnetism

• Magnetic poles, attraction and repulsion
• Magnetic fields by plotting with compass, representation by field lines
• The Earth's magnetism, compass and navigation
• The magnetic effect of a current, electromagnets and DC motors.

Matter: physical changes

• Conservation of material and of mass, and reversibility, in freezing, melting, evaporation, sublimation, condensation and dissolving
• Similarities and differences, including density differences, between solids, liquids and gases
• Brownian motion in gases
• Diffusion in liquids and gases driven by differences in concentration
• The difference between chemical and physical changes.

Particle model

• The differences in arrangements, motion and closeness of particles explaining changes of state, shape and density; the anomaly of ice-water transition
• Atoms and molecules as particles.

Energy in matter

• Changes with temperature in motion and spacing of particles
• Internal energy stored in materials. 

Space physics

• Gravity force, weight = mass x gravitational field, on Earth and different planets and stars; gravity forces between Earth and the moon, and between Earth and the sun
• Our sun as a star; other stars in our galaxy; other galaxies
• The seasons and the Earth's tilt; day length at different times of the year and in different hemispheres
• The light year as a unit of astronomical difference.