S3.6.3 For the adult
Separating mixtures
How can you get salt back out of sea water, or take the mud out of muddy water?
What this chapter teaches
The parts of a mixture are not joined, so they can be separated. A sieve separates by size. A filter removes a solid that has not dissolved. Evaporating gets back a dissolved solid. Chromatography splits the coloured substances in an ink.
Three questions to ask
There is no one right wording. Listen for the idea.
- Which method would you use for sand in water, and why?
- Why does filtering not take salt out of salty water?
- What does it tell us when a spot of ink splits into colours?
After the chapter, the learner can
- Choose sieving, filtering or evaporating to separate a mixture
- Get salt back from salty water by leaving it in the sun
- Separate the colours in ink using paper and water
What they copy into their notebook
Sieve to separate by size. Filter to remove a solid. Evaporate to get a dissolved solid back. Chromatography splits an ink into its colours.