Basic 2 · Science · Materials
Separating Solid–Solid Mixtures
In this topic you will separate solid–solid mixtures using picking, sieving and winnowing.
By the end of these notes you should be able to:
- Name ways of separating solid mixtures
- Separate a mixture using a sieve
- Choose the right method for a mixture
What you already know
- Solid–solid mixtures
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
- Strand
- Diversity of Matter
- Sub-strand
- Materials
- Indicator
- B2.1.2.3.1 – Describe a solid–solid mixture and explain how to separate the components
Introduction
Grandmother pours rice from a tray up and down in the wind. The light chaff blows away. She is separating a mixture.
1. Ways to Separate
| Method | How it works | Example |
|---|---|---|
| picking | pick out the bigger pieces by hand | stones from beans |
| sieving | small pieces fall through holes | sand from stones |
| winnowing | wind blows away light parts | chaff from rice |
| magnet | pulls out iron pieces | iron nails from sand |
2. Choosing a Method
Look at the size and weight of the parts.
- Different sizes: use a sieve or picking.
- One part is light: use winnowing.
- One part is iron: use a magnet.
Safety: Wash your hands after handling sand and soil.
New words
- separate
- To take the parts of a mixture apart.
- sieve
- A tool with small holes.
- winnow
- To use wind to blow away light parts.
- chaff
- The light outer covering of grains.
Summary
- We can separate solid mixtures by picking, sieving, winnowing or with a magnet.
- Choose the method by size, weight or iron.
- Winnowing blows away light chaff.
Class activity: Separation Challenge
- Mix maize grains and beans.
- Separate them by picking.
- Mix sand and small stones. Separate them with the sieve.
You need: Maize grains, Beans, Locally woven sieve, Calabash bowls
Exercises
Answer in your exercise book first, then check your answers.
1. Which tool has small holes?
- A. Sieve
- B. Spoon
- C. Cup
- D. Plate
Show answer
Answer: SieveSmall parts fall through the holes.2. How is chaff removed from rice?
- A. Winnowing
- B. Boiling
- C. Freezing
- D. Painting
Show answer
Answer: WinnowingWind blows the light chaff away.3. We can pick stones out of beans by hand.
- A. True
- B. False
Show answer
Answer: TrueStones are easy to see and pick.4. A magnet can pull sand out of a mixture.
- A. True
- B. False
Show answer
Answer: FalseMagnets pull iron, not sand.5. To take the parts of a mixture apart is to ______ them.
Show answer
Answer: separateThat is separating.6. How would you separate sand and stones?
Show answer
Answer: Use a sieve.Sand passes through; stones stay.
Homework
- Watch someone at home pick stones from rice or beans. Write the method used.