7G Solids, Liquids and Gases
Lesson 4: Diffusion
Learning objectives
 To apply a model to new phenomena to explain behaviour
 That gas particles are moving around all the time
Learning outcomes
 To explain their observations in terms of particle theory
Resources
Worksheets – “Diffusion”, coloured pencils.
Demonstration: air freshener or perfume; potassium manganate (VII) in agar jelly
and ammonia and hydrochloric acid.
Wipe-out game cards.
Lesson Outline
1. Starter: demonstration air freshener or perfume.
2. Demonstration: Diffusion of Agar and potassium manganate (VII) and
diffusion ammonia and hydrochloric acid.
 Seek explanations – ammonia is a gas, ask one pupil to add particles
to drawing of tube on the board.


Go on to add hydrochloric acid (gas) particles to the other end.
Describe and go on to explain what has happened to the particles of
the two substances.
3. Role-play. Have pupils in white shirts in one corner and pupils in black tops in
the other and see them ‘diffuse’.
4. Worksheet “Diffusion”. Add particles to comic strips using two different
coloured pencils.
5. Plenary: wipe-out game – to summarise topic. Blue-tac cards to board and
invite pupils to identify correct statements. Use CASE style questioning
techniques to get the most from the activity.