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Science at key stage 3 (Year 7)
Unit 7G: Particle model of solids, liquids and gases
Section 3: What are the differences between solids, liquids and gases?
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Objectives |
| Children should learn: |
- that materials can be classified as solid, liquid or gas, but that some are difficult to classify
- to evaluate their own theory in the light of evidence
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Activities |
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Outcomes |
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Children: |
- Give pupils a range of materials to classify as solid, liquid or gas. Include some materials that pupils find difficult to classify,
eg paper, sand, jelly, talc, toothpaste, tomato sauce, reusable adhesive, etc. Tell pupils they should be prepared to justify their classification, making explicit the criteria they used. Ask them to list the properties of solids, liquids and gases and use this to develop a key for classifying materials.
- Ask pupils to imagine they can see what the materials are made from by using an immensely powerful microscope and, in groups, to discuss and create their own theory or model of what the materials are made from. Invite pupils to communicate these to the class. At this stage, help pupils identify inconsistencies between theory and evidence, but do not give the correct particle theory.
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- classify materials and justify their classification in terms of properties of solids, liquids and gases
- explain why some materials are difficult to classify
- generate descriptions of solids, liquids and gases consistent with the evidence and their scientific knowledge,
eg a solid is made of tiny grains all glued together
- design a key to classify materials as solid, liquid or gas
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Points to note |
- This activity is familiar from key stage 2. The emphasis here is on pupils deciding the criteria for classification, thinking about whether these can be used in the cases they have and, if necessary, amending or refining their criteria.
- One group may classify one substance as solid, while another may say it is liquid; this provides a good discussion point about the limitation of the solid/liquid/gas system for classifying and the need for clear criteria.
- Many pupils will already have heard of particles; they may use terms for them,
eg
atom,
molecule, perhaps incorrectly.
- Some may confuse microbes, cells and particles and the differences will need to be made explicit (see unit 7A 'Cells').
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This unit is divided into sections. Each section contains a sequence of
activities with related objectives and outcomes. You can view this unit by
moving through the sections or print/download the whole unit.
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