Class 6 Science Chapter 9 Methods of Separation – Revision Notes

Ten separation methods run through Class 6 Science Chapter 9, from handpicking stones out of grain to using a soop for winnowing, and this page condenses each one into a quick-glance summary.

Last Updated: September 23, 2026

Why We Separate Mixtures

• To remove an unwanted or harmful component (e.g., stones from grain).
• To separate two different, both-useful components (e.g., butter from buttermilk).

The 10 Separation Methods in This Chapter

• Handpicking — by sight, for small quantities of impurity (stones from grain)
• Threshing — beating stalks to loosen grain
• Winnowing — wind separates light husk from heavy grain (using a soop)
• Sieving — particle size (flour sifting, sand from pebbles)
• Sedimentation — heavier solids settle at the bottom
• Decantation — pouring off the clear liquid after sedimentation
• Filtration — porous filter removes insoluble solids from a liquid; output is called the filtrate
• Evaporation — recovers a dissolved solid (like salt) by turning the liquid to vapour
• Churning — agitation separates butter from buttermilk
• Magnetic separation — a magnet pulls out magnetic material (like iron)

Not covered in Class 6: distillation, sublimation, chromatography, centrifugation — these come in later classes.

Key Terms

• Mixture: two or more substances combined without a chemical reaction.
• Filtrate: the liquid that passes through a filter during filtration.
• Sedimentation: the settling event (a state), while decantation is the deliberate pouring-off action that follows it.

Common Mistakes to Avoid

• Filtration cannot remove a dissolved substance like salt — only evaporation can.
• Sieving works on solid-solid mixtures; it cannot separate two liquids or a dissolved solid.
• Threshing and winnowing are not interchangeable — threshing loosens grain from stalks; winnowing then blows away the husk.
• Decantation alone may leave fine particles behind — filtration is often needed afterward for a fully clear liquid.

One-Line Summary

Every method in this chapter separates a mixture using a specific physical difference between its parts — size, weight, magnetism, or solubility — and everyday Indian examples (winnowing grain, churning curd, filtering tea) show these principles in action.

Frequently Asked Questions

Why is it sometimes necessary to separate the components of a mixture?
Separating a mixture is often necessary to obtain a pure substance, to remove unwanted or harmful components, or to recover a valuable material, since most substances in nature exist mixed together.

What is the difference between filtration and evaporation as separation methods?
Filtration separates an insoluble solid from a liquid using a filter that traps solid particles, while evaporation separates a dissolved solid from a liquid by heating it until the liquid turns to vapour.

Written by Satish

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