Science · KS3 · Particles
KS3 Particles Science for Years 7–9
The particle model is a scientific model used to explain observations about solids, liquids and gases. It becomes useful when pupils connect the invisible model to measurable behaviour such as changes of state, diffusion and gas pressure.
What to understand in this topic
- compare particle arrangement and movement in solids, liquids and gases
- use particle motion to explain diffusion
- describe changes of state without inventing new particles
- link macroscopic observations to a simple particle-model explanation
A common point of confusion
Heating a substance does not make its individual particles swell. In the model, changes in movement and spacing explain expansion and changes of state; the particles themselves are not drawn as growing larger.
Try a quick example
Question: Why can the smell of perfume spread across a room even when no one carries it?
Answer: Gas particles move randomly and diffuse through the air.
Diffusion is the net movement and mixing of particles due to their random motion.
This is a fixed educational example on the page, not a customer result and not a live tutor response.
What a parent can try at home
Ask the child to draw particle diagrams for a solid, liquid and gas using the same-sized dots. Then ask what should change between diagrams: arrangement, spacing and movement—not particle identity or size.
How NexEdu practises this
NexEdu can practise model-based explanations through multiple-choice questions. Practical demonstrations and teacher explanations remain important because the tutor does not perform or observe experiments.
NexEdu provides guided questions throughout the child’s available daily tutoring time. A hint can follow an incorrect answer, and two consecutive incorrect answers trigger a brief reteach before practice continues. Same-day topic progress can resume where the child left off.
Related learning
About the information on this page
The educational summary is written to help parents understand the topic and its place in the National Curriculum in England. Product statements describe the current NexEdu implementation; they are not promises of a particular grade, score or rate of progress.