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gas
Gas particles spread through the available space.
Class 6 · English Version · General science
2026 Class 6 Science · English Version · Chapter 7 · Chapter companion part
Chapter 7: Properties of Matter and External Effect
Choose materials by their properties and describe changes caused by heating or force.
Class 6 English Version chapter companion with expanded teaching, 20 written tasks and a notebook challenge. Further independent assessment and teacher-reviewed practical work remain; this is not complete textbook coverage.
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Learn the idea
Matter has mass and occupies space. A solid usually keeps its shape and volume; a liquid keeps its volume but takes the container’s shape; a gas spreads to fill its container. Hardness, flexibility, density and conductivity describe different properties. A soft solid can still have a definite shape.
Materials for a purpose
Most metals conduct heat and electricity well and can be formed into useful shapes. Many non-metals are poor electrical conductors, but there are exceptions: graphite conducts. A material is chosen for a combination of properties. Copper carries current in a cable while an insulating cover reduces contact with the conductor.
Heating and cooling
Heating can cause expansion, melting or boiling; cooling can cause contraction, condensation or freezing. Pure water freezes near 0°C and boils near 100°C at standard atmospheric pressure. Pressure and impurities can change these values. During melting of a pure substance at steady pressure, energy can change state without raising temperature.
Safe comparisons
Use supplied temperature data and images for home practice. Flames, hot liquids, unknown chemicals and mains electricity are teacher-supervised demonstrations, not child tasks. Mechanical force can stretch, bend or deform a material; compare shape changes without assuming every change is permanent.
Compare properties with a purpose
Hardness is resistance to scratching; flexibility describes bending. Brittleness is a tendency to break rather than deform. Density is mass per unit volume: divide mass by volume using stated units. These are different properties, so a shiny material is not automatically hard, heavy or suitable for every purpose. Compare samples under similar conditions and record what the evidence actually shows.
Separate heat from electric-current tests
Thermal conductivity describes how readily heat transfers through a material; electrical conductivity concerns electric current. A classroom electrical comparison needs a complete low-voltage circuit and a suitable indicator, with other parts kept alike. A bulb staying off can also mean a loose wire or a failed bulb. Treat metal/non-metal trends as patterns with exceptions, and reuse materials rather than waste them.
Interpret heating and cooling records
A melting point concerns a solid changing to liquid; a boiling point concerns boiling throughout a liquid. Evaporation can occur below boiling point at a surface. A pure substance can show a steady temperature during a state change at a fixed pressure; mixtures such as everyday wax may change over a range. Cooling transfers energy to cooler surroundings. Freezing is one possible result of cooling, not a synonym for every temperature decrease.
Read, deform and investigate safely
Use the same observation intervals, read a thermometer within its range and record time from a stated start. An elastic deformation is reversed when the force is removed; a permanent deformation remains. Use supplied results or safe paper/rubber models. Hot materials, flame tests, striking brittle samples and electrical experiments need a teacher’s appropriate setup; never test a wall socket. No practical success is claimed from a paper answer alone.
Worked example
A saucepan may use a metal body to transfer heat and a heat-resistant handle to slow heat transfer to a hand. This is a choice of properties, not a claim that the handle can never become hot.
- Identify the evidence, quantity or structure in the question.
- Write a labelled method or explanation; include units where needed.
- Check the model, explain one correction, then attempt the independent task.
Check a common mistake
Temperature is not the same quantity as energy. A steady temperature during a change of state does not mean no energy is being transferred.
Density from supplied readings
A sample has mass 18 g and volume 6 cm³. Density = 18 ÷ 6 = 3 g/cm³: each cubic centimetre of that sample has a mass of 3 g under the stated conditions.
A state-change plateau
A pure-substance heating model gives temperatures 20, 40, 60, 60 and 80°C at equal intervals. During the two 60°C readings, solid and liquid are both present. That supports a melting point of 60°C in this model, not a universal value for all materials.
Your written practice
Show your working on paper and enter your answer here. If it does not match, compare the model and try again.
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liquid
A liquid takes the shape of the part of the container it occupies.
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melting
Heating can supply the energy needed for melting.
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condensation
Cooling can produce condensation.
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100
About 100°C; pressure affects the boiling point.
Write in your own words. A guardian or teacher should review this response.
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The metal conducts current and the cover reduces unwanted contact with it.
State both roles; do not propose touching live wiring.
Write in your own words. A guardian or teacher should review this response.
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Graphite is a non-metal that conducts electricity. General patterns can have exceptions.
Give the counterexample and avoid replacing it with another absolute claim.
Write in your own words. A guardian or teacher should review this response.
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It can receive energy used to change state rather than raise temperature.
Distinguish energy transfer from temperature change.
Take it further
Apply the idea in a new situation and explain your method. Open writing needs a guardian or teacher to review it.
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3
24 ÷ 8 = 3 g/cm³; this is mass per cubic centimetre for the supplied sample.
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45
75 − 30 = 45°C.
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55
The temperature stays at 55°C while the supplied model changes from solid to liquid.
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evaporation
Evaporation can occur at the surface without the whole liquid boiling.
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elastic
Elastic deformation is reversed when the force is removed.
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hardness
Hardness and flexibility measure different properties.
Write in your own words. A guardian or teacher should review this response.
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A broken bulb, loose connection or an unsuitable setup could explain the result. Check the circuit with a known conductor and compare like conditions.
Name another cause and a suitable control; do not propose mains testing.
Write in your own words. A guardian or teacher should review this response.
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Waxes can have different compositions and melt over ranges. The particular sample and conditions matter.
Distinguish a supplied observation from a universal property claim.
Write in your own words. A guardian or teacher should review this response.
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Boiling occurs throughout the liquid under the relevant conditions; evaporation takes place at the surface and can occur below boiling point.
Explain both processes rather than saying all vapour means boiling.
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Good heat transfer can help the body heat food but can make a handle uncomfortable or unsafe to hold; insulation and heat resistance matter for the handle.
Relate the properties to two different jobs.
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Use similar dimensions and the same gentle applied load or bend, record the shape change and whether each returns after release. Use a teacher-approved or supplied setup.
State what changes, what stays alike and what is recorded.
Write in your own words. A guardian or teacher should review this response.
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No. Cooling means energy is transferred to cooler surroundings; freezing requires a change to solid under the relevant conditions.
Distinguish temperature decrease from state change.
Your science notebook challenge
Make a materials table for three supplied samples with separate columns for hardness, flexibility and conductivity evidence. Calculate a supplied density, interpret a heating record and explain one fair-test control. Review any real equipment use with a teacher.
Review with a guardian or teacher
- Use an observation, labelled diagram or stated data.
- Explain how the evidence supports your answer.
- Record one limitation or correction with a guardian or teacher.
Keep your work on paper or in a local file. This page does not upload it or automatically grade the project.
Chapter companion and further study
This original Kidemy practice follows the topic order of 2026 Class 6 Science · English Version, chapter 7, printed pages 58–69. It does not replace the complete chapter or its practical teaching.
Official book catalogue and source →
Continue with your book or teacher
- Independent material-choice and state-change assessment
- Teacher-reviewed instrument readings, conductivity and deformation observations
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