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Term 1 Topic 4 Rates of dissolving – Teachers for Tech and ScienceSkip to content
factors that affect the rate (time taken) of dissolving:
temperature of the mixture
stirring or shaking the mixture
grain size of the solute
Teacher Input 1
Greet the learners.
Ask them if they can remember what was discussed in the last lesson or lessons.
Do a brief overview of the previous lessons on “Solutions and special mixtures. Ask your learners the following questions:
When is a mixture also a solution?
Answer: When one substance dissolves into the other.
What is the substance that we can see called?
What substance has dissolved?
Give an example of a soluble solute (solids).
Answers could include: Sugar (solute) can dissolve in water (solvent).
What is a saturated solution?
Answer: When no more solute can dissolve in a solution - e.g. too much sugar in my tea.
Give examples of insoluble substances?
Answers could include: Water and oil, oil-based paint and water, sand and water, curry powder and water.
Tell learners that they are going to learn about dissolving today.
Tell learners that they are going to learn about the difference between dissolving and melting.
Tell learners that they are first going to look at a video clip to remind them how a solid, a liquid and a gas differ from each other. They are going to see how the states change, which means, when a substance changes from one state (e.g. solid) to another (e.g. liquid).