Class 5 General Science
Explore atoms, elements, compounds, mixtures, chemical reactions, density, buoyancy, forces, Newton’s ideas, gravity, energy, light, sound, electricity, electromagnetism, Earth and space through 30 progressive General Science lessons that develop scientific reasoning and investigation skills.
⚛️ Atoms, Elements and Matter
Understanding Atoms as Building Blocks of Matter
An atom is a very small unit from which ordinary matter is built. Atoms are far too small to see with our eyes. Different kinds of atoms can join together in different ways to form the enormous variety of substances around us.
Matter → Made of atoms
Atoms → Can combine to form molecules and other structures
Use coloured balls or circles to represent atoms. Join several models together to show how atoms can form larger structures.
Models of atoms are useful learning tools, but real atoms are far smaller and more complex than classroom models.
Introduction to Elements
An element is a pure substance made of only one type of atom. Scientists have identified many elements, and each element has its own name and chemical symbol.
Hydrogen → H
Oxygen → O
Carbon → C
Iron → Fe
Choose five familiar elements and make cards showing their names and chemical symbols.
An element cannot be broken into simpler substances by ordinary chemical reactions.
Introduction to Compounds
A compound is a pure substance formed when atoms of two or more different elements are chemically combined in fixed proportions. A compound can have properties very different from the elements from which it is formed.
Water → Hydrogen and oxygen chemically combined
Carbon dioxide → Carbon and oxygen chemically combined
Use differently coloured circles to create simple models of water molecules containing hydrogen and oxygen atoms.
The elements in a compound are chemically bonded, not simply mixed.
Comparing Elements, Compounds and Mixtures
Elements and compounds are pure substances, while mixtures contain two or more substances physically combined. Components of mixtures can often be separated by physical methods.
Element: One type of atom
Compound: Different elements chemically combined
Mixture: Substances physically combined
Classify examples such as oxygen, pure water, air and sand mixed with iron filings.
A compound has a definite composition. The proportions of components in a mixture can vary.
Exploring Methods of Purifying Substances
Purification involves separating unwanted substances from a material or separating components of a mixture. The appropriate method depends on differences in physical properties.
Filtration → Separates suitable insoluble solids from liquids
Evaporation → Can recover a dissolved solid
Distillation → Can separate substances using differences in boiling behaviour
Decide which separation method would be suitable for sand and water or for recovering salt from a salt solution.
Heating and distillation activities require proper equipment and adult supervision.
🧪 Chemical Reactions and Changes
Understanding Chemical Reactions for Beginners
A chemical reaction is a process in which starting substances are changed into one or more new substances. The atoms are rearranged into new combinations during the reaction.
Iron rusting • Fuel burning • Some cooking processes
Examine pictures of physical and chemical changes and decide which examples are likely to produce new substances.
Chemical reactions rearrange atoms; they do not simply make matter disappear.
Recognising Evidence of Chemical Change
Scientists use observations to determine whether a chemical reaction may have occurred. Possible evidence includes unexpected colour change, gas production, temperature change, light emission or formation of a new solid.
Gas bubbles • New colour • New solid • Temperature change • Light
Why are bubbles from boiling water not by themselves proof of a chemical reaction?
A single observation does not always prove that a chemical reaction occurred. Evidence must be interpreted carefully.
⚖️ Mass, Volume, Density and Buoyancy
Understanding Mass and Volume
Mass describes the amount of matter in an object, while volume describes the amount of space it occupies. These are different physical quantities and are measured using different units.
Volume: millilitres (mL), litres (L), cubic centimetres (cm³)
Measure the mass of a safe object with a balance and determine its volume using an appropriate method.
Two objects can have the same volume but different masses.
Introduction to Density
Density describes how much mass is contained in a given volume. For a uniform material, density can be calculated by dividing mass by volume.
Object A and Object B have the same volume.
If Object A has more mass, it has greater average density.
Compare two equal-sized classroom objects made from different materials. Measure their masses and discuss their densities.
Density depends on both mass and volume, not on mass alone.
Investigating Buoyancy
An object placed in a fluid experiences an upward buoyant force. Whether an object floats or sinks depends on the balance of forces and is closely related to the object’s average density compared with the fluid.
A steel ship can float even though steel itself is denser than water because the ship’s hollow shape gives the whole ship a lower average density and allows it to displace a large volume of water.
Use modelling clay to make a compact ball and then a hollow boat shape. Test both carefully in water.
Floating depends on more than whether an object feels heavy or light.
🚀 Forces and Motion
Understanding Balanced and Unbalanced Forces
Forces acting on an object can combine. When the overall or net force is zero, the forces are balanced. When the net force is not zero, the forces are unbalanced and the object’s velocity changes.
A book resting on a table has downward gravitational force balanced by the upward support force.
Unbalanced:
A pushed toy accelerates when the forces on it are not balanced.
Draw arrows to represent forces acting on a stationary book and a moving toy being pushed.
Balanced forces do not require an object to be stationary. An object can move at constant velocity when the net force is zero.
Exploring Newton’s Ideas About Motion
Isaac Newton developed important laws describing how forces affect motion. A key idea is that an object’s motion changes when an unbalanced net force acts on it.
1. Objects resist changes in their motion — inertia.
2. Greater net force produces greater acceleration for the same mass.
3. Forces between interacting objects occur in equal and opposite pairs.
Why does an empty shopping trolley usually accelerate more easily than a heavily loaded trolley when similar forces are applied?
Newton’s laws describe relationships between forces and motion.
Understanding Gravity and Weight
Gravity is an attractive force between masses. Weight is the gravitational force acting on an object. An object’s mass and weight are related but are not the same quantity.
Mass → Amount of matter; measured in kilograms
Weight → Gravitational force; measured in newtons
An astronaut’s mass remains essentially the same on Earth and the Moon, but why is the astronaut’s weight smaller on the Moon?
Weight changes when gravitational field strength changes; mass does not change merely because an object moves to another location.
⚡ Mechanical Energy and Energy Changes
Understanding Mechanical Energy
Mechanical energy is associated with an object’s motion and position. In simple situations it can be considered as the combination of kinetic and potential energy.
A swinging pendulum continually changes between kinetic and gravitational potential energy.
Observe a playground swing and identify where its motion is fastest and where it reaches its greatest height.
Energy can move between different stores and forms during motion.
Exploring Kinetic Energy
Kinetic energy is the energy associated with motion. The amount of kinetic energy depends on an object’s mass and speed. Increasing speed has a particularly strong effect on kinetic energy.
Stationary ball → No translational kinetic energy
Moving ball → Has kinetic energy
Faster ball of the same mass → More kinetic energy
Roll the same toy car at different speeds and discuss which motion represents greater kinetic energy.
Both mass and speed affect kinetic energy.
Exploring Potential Energy
Potential energy is energy associated with position or configuration. An object raised above the ground can have gravitational potential energy because of its position in Earth’s gravitational field.
Raised book → Gravitational potential energy
Stretched elastic band → Elastic potential energy
Compare the gravitational potential energy of the same object at two different heights.
For the same mass and local gravity, raising an object higher increases its gravitational potential energy relative to the chosen reference level.
Understanding Energy Transformation
Energy can be transferred and transformed from one form or store to another. Devices often perform several energy transformations at the same time.
Torch → Chemical energy → Electrical transfer → Light + heating
Electric fan → Electrical energy → Motion + sound + heating
Choose three household devices and identify their main useful energy outputs.
Energy is conserved overall, although some energy often becomes less useful for our intended purpose, commonly through heating.
💡 Light, Reflection and Refraction
Exploring Light Reflection with Ray Diagrams
A ray diagram uses straight lines and arrows to represent the direction in which light travels. When a ray reflects from a plane mirror, the angle of incidence equals the angle of reflection.
Incident ray → Incoming light
Normal → Imaginary line perpendicular to the mirror
Reflected ray → Light travelling away from the mirror
Draw a mirror line and a normal. Add an incident ray and then draw its reflected ray at the matching angle.
Angles of incidence and reflection are measured from the normal, not from the mirror surface.
Introduction to Refraction
Refraction is the change in direction of light when it passes from one transparent medium into another at an angle because its speed changes.
A pencil partly placed in water may appear bent at the water’s surface because light is refracted as it passes between water and air.
Place a pencil in a transparent glass of water and observe it from the side.
The pencil itself has not bent. The apparent change is caused by the way light changes direction.
Understanding How Lenses Affect Light
Lenses are transparent objects with curved surfaces that refract light. Convex and concave lenses affect parallel light rays differently.
Convex lens → Can bring parallel rays toward a focus
Concave lens → Causes parallel rays to spread apart
Examine teacher-provided lenses and compare how objects appear through them.
Never look at the Sun through a lens, magnifying glass, binoculars or telescope without specialised approved solar equipment.
🔊 Sound Waves
Understanding Sound Waves
Sound is a mechanical wave produced by vibrating sources. The disturbance travels through a material medium as particles transfer energy to neighbouring particles.
Vibrating source → Disturbance in medium → Sound travels → Ear detects the sound
Use a stretched spring model or teacher-guided demonstration to represent compressions moving through a medium.
Sound transfers energy through a medium without transporting the medium itself from the source all the way to the listener.
Exploring Frequency and Amplitude
Frequency describes how many complete vibrations occur each second and is measured in hertz (Hz). Amplitude describes the maximum size of the vibration from its equilibrium position.
Higher frequency → Generally higher perceived pitch
Greater wave amplitude → Generally greater sound intensity
Draw two simple waves with different frequencies and another pair with different amplitudes.
Frequency and amplitude are different wave properties.
⚡ Electricity and Electromagnetism
Understanding Electric Current
Electric current describes the rate of flow of electric charge. In a simple circuit, current can flow when there is a complete conducting path and a suitable source such as a cell or battery.
Battery → Conducting wires → Lamp → Return path to battery
Trace the complete path around a teacher-provided circuit diagram.
A break in a simple circuit interrupts the conducting path.
Constructing Series Circuits
In a simple series circuit, components are connected one after another in a single conducting path. The same current passes through each component in that single path.
Battery → Lamp 1 → Lamp 2 → Battery
Use only low-voltage classroom components to connect two small compatible lamps in series.
If the single conducting path is broken, current stops throughout that simple series circuit.
Introduction to Parallel Circuits
A parallel circuit contains branches that provide more than one path for electric current. Components connected on different branches can operate more independently than components in a single series path.
Main path → Splits into branches → Branches rejoin
Compare teacher-provided diagrams of simple series and parallel circuits.
Series circuits have one main current path; parallel circuits contain multiple branches.
Understanding Electrical Safety Scientifically
Electric current can be dangerous when it passes through the human body. Electrical systems therefore use insulation, protective devices and safe operating practices to reduce risk.
Keep liquids away from electrical devices.
Do not use damaged plugs or wires.
Never insert objects into electrical sockets.
Tell an adult about damaged electrical equipment.
Create an electrical-safety poster showing safe and unsafe behaviours.
Student circuit investigations should use only approved low-voltage equipment under appropriate supervision. Never experiment with household mains electricity.
Exploring Electromagnetism
Electric current produces a magnetic field around a conductor. A coil of current-carrying wire can create a stronger and more useful magnetic effect, especially when used with a suitable iron core.
Electric current through coil → Magnetic field
Using a suitable low-voltage battery, insulated wire and an appropriate iron core, observe a simple classroom electromagnet.
Simple coils can become warm if connected for too long. Use only teacher-approved low-voltage equipment and disconnect the circuit after brief observations.
🌍 Earth, Gravity and Space
Understanding Earth’s Gravity and Orbit
The Sun’s gravitational attraction continually changes the direction of Earth’s motion, helping keep Earth in its orbit around the Sun. Earth also exerts gravitational attraction on the Sun.
Earth has forward motion while the Sun’s gravity continually changes Earth’s direction, producing an orbit.
Draw the Sun and Earth’s orbital path. Add arrows representing Earth’s motion and gravitational attraction toward the Sun.
An orbit is not caused by the absence of gravity. Gravity is essential to Earth’s orbital motion.
Investigating the Earth–Moon–Sun Relationship
Earth orbits the Sun, while the Moon orbits Earth. The changing relative positions of the Sun, Earth and Moon help explain observable patterns such as Moon phases and eclipses.
Earth → Orbits the Sun
Moon → Orbits Earth
Moon phases → Different views of the Moon’s sunlit half
Eclipses → Occur during particular alignments
Use a lamp as the Sun and balls as Earth and Moon to explore how illumination changes as their relative positions change.
Moon phases are not normally caused by Earth’s shadow. Earth’s shadow on the Moon is associated with a lunar eclipse.
🔬 Applying the Scientific Method
Applying the Scientific Method to an Investigation
Scientific investigations use systematic observations, measurements and evidence to answer questions. There is no single rigid procedure used in every branch of science, but controlled investigations often follow a useful sequence of steps.
Question: Does ramp height affect how far a toy car travels?
Independent variable: Ramp height
Dependent variable: Distance travelled
Controlled variables: Same car, ramp surface, release method and measurement procedure
1. Ask a clear, testable question.
2. Use previous observations or research.
3. Make a prediction or hypothesis when appropriate.
4. Identify variables.
5. Design a fair and safe procedure.
6. Take measurements and record observations.
7. Repeat trials when useful.
8. Organise the results in tables or graphs.
9. Look for patterns in the evidence.
10. Draw a conclusion supported by the results.
11. Identify possible limitations or improvements.
12. Communicate what you discovered.
Science is based on evidence. A prediction that is not supported by the results is still valuable because the evidence helps us improve our understanding.