Key stage 2
Key stage 1
- To understand that some solids dissolve and some do not.
- To understand that some changes are reversible and some are irreversible.
Sc1, 2l; Sc3, 2a, 2d.
- Online activities:
- Learning Zone Broadband Class Clips:
- Other resources:
- 'Post-it' notes
- Interactive whiteboard
- Computers (one for each group)
- Cards showing the words 'Reversible' and 'Irreversible'
You will need Adobe Acrobat reader to access the PDF files. BBC Webwise has a complete guide to downloading and installing Adobe Acrobat reader.
- Watch Learning Zone Broadband Class Clips - Changes in the state of materials.
- Ask the children what they are learning (changes of state).
- Ask them to list on a post-it note everything they know about dissolving.
- Use this information to guide discussion of solutions and how to separate them.
- Explain to the children that they are going to investigate some solids to see which dissolve in water and which do not.
- Bring up the Bitesize reversible and irreversible activity on the interactive whiteboard.
- Ask the children to predict which of the solids in the menu (salt, flour, sugar, coffee, sand) will dissolve in the water to form a solution and which will not dissolve.
- Write the predictions on the board.
- Ask the higher ability group to write a hypothesis.
- Show the children how to add a substance to the water in the Bitesize reversible and irreversible activity by clicking and dragging a solid from the menu into the beaker.
- Click on the reversing button. Show the children how to drag substances from the menu onto the screen and try to reverse changes that have taken place.
- Divide the children into groups with a computer for each group.
- Let the groups work through the dissolving and reversing screens, following the tasks that are written (and read aloud) at the top of the screen.
- Place the Reversible and Irreversible cards around the room throughout the learning session. Shout out changes in state (eg melting chocolate) and ask the children to run to the correct word.
- Ask which solids dissolved and which did not. Compare the children's observations with their earlier predictions.
- Ask how the change brought about by mixing a soluble or insoluble substance with water can be reversed (by filtering or by evaporating).
- Ask which changes were reversible and which were irreversible in the reversing part of the activity. Make a list.
- Tell the children that irreversible changes result in the formation of new materials, which may be desirable (eg a baked cake) or undesirable (eg a rusty bike).
- Play the Bitesize reversible and irreversible quiz as a class to assess learning.
- Ask the children to complete the Reversible and irreversible worksheet (PDF 294KB). Explain that they must write which of the changes shown are reversible and which are irreversible.
- Complete the Pod's Mission solids and liquids game as a class.
Ask the children to make a list of the reversible and irreversible changes they observe in their home or garden.