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Class 6 Science Chapter 9 Methods of Separation in Everyday Life — Formulas & Key Points

Class 6 Science Chapter 9 is unique—it has no algebraic formulas, but it has process rules and decision logic. Every CBSE exam question asks 'which method separates X from Y?' or 'why does filtration work for muddy water but not salty water?' This formula sheet organizes all seven methods into tables, gives you step-by-step process flows, highlights common exam traps, and provides three mini-examples so you can confidently pick the right technique in two seconds during the test.

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Key takeaways

  • ✓Threshing separates seeds from dry husk by beating; winnowing uses wind to blow away lighter husk after threshing.
  • ✓Sieving works for solids of different sizes; filtration separates insoluble solids from liquids using porous barriers.
  • ✓Sedimentation is waiting for heavy particles to settle; decantation is carefully pouring off the clear liquid layer.
  • ✓Evaporation removes liquid by heating to leave behind dissolved solids like salt; magnetic separation pulls iron from non-magnetic mixtures.
  • ✓In exams, you must match the mixture type to the correct method—NCERT questions often test this decision-making skill.
  • ✓No single method works for all mixtures; sometimes you combine two or three methods in sequence for complete separation.
  • ✓CBSETUTOR.ai offers a flat ₹999/month AI tutor for every CBSE class (6-12) with photo-upload solving and 24×7 doubt clearing, with a 3-day free trial.

Master Table: All Separation Methods at a Glance

This single table is the heart of the chapter. Print it, stick it above your study desk, and memorize the 'Best For' column. In the 2024 CBSE Class 6 final, 4 out of 6 marks from this chapter came from matching a mixture to the correct method. Each row shows the method name, what it does, when to use it, and a one-line example. Notice that some methods work on solid-solid mixtures (threshing, winnowing, sieving, magnetic separation) while others work on solid-liquid mixtures (filtration, sedimentation, decantation, evaporation). If the exam says 'salt dissolved in water,' evaporation is your answer because salt is a dissolved solid, not suspended. If it says 'sand in water,' filtration or sedimentation works because sand does not dissolve.
  • Threshing: Beating dried crop to free seeds from husk—used in wheat, rice, pulses after harvest.
  • Winnowing: Using wind to blow away light husk from heavier seeds—follows threshing on the farm.
  • Sieving: Shaking mixture through a mesh to separate by particle size—flour from lumps, sand from pebbles.
  • Filtration: Pouring liquid through porous barrier to trap solid particles—muddy water through cloth or filter paper.
  • Sedimentation: Letting heavy particles settle to the bottom under gravity—leaving muddy water undisturbed.
  • Decantation: Pouring off clear liquid without disturbing settled sediment—follows sedimentation step.
  • Evaporation: Heating liquid until it vaporizes, leaving dissolved solid behind—seawater to salt crystals.
  • Magnetic Separation: Using magnet to pull iron or steel from non-magnetic materials—iron filings from sand.

Detailed Process Steps for Each Method

Exams sometimes ask 'describe the process of filtration in four steps' or 'draw and label a sieving setup.' Here are the exact steps NCERT expects. For threshing: (1) Spread dried crop on hard ground or mat. (2) Beat with sticks or run animals/machines over it. (3) Seeds loosen and fall; husk breaks up. (4) Collect seeds in one pile. For winnowing: (1) Take threshed mixture of seeds and husk. (2) Stand in open air or use a fan. (3) Pour mixture from height or throw it up. (4) Wind blows away light husk; heavy seeds fall straight into container. For sieving: (1) Choose sieve with hole size between the two particle sizes. (2) Pour mixture onto sieve. (3) Shake or tap gently. (4) Smaller particles fall through; larger stay on top. For filtration: (1) Fold filter paper into cone and place in funnel. (2) Pour mixture slowly into funnel. (3) Liquid (filtrate) drips through; solid (residue) stays on paper. (4) Collect filtrate in beaker below. For sedimentation and decantation: (1) Pour cloudy liquid into tall container. (2) Leave undisturbed for 30 minutes to several hours. (3) Heavy particles sink to bottom; liquid clears. (4) Tilt container and pour clear liquid slowly into another vessel (decantation). For evaporation: (1) Pour solution into shallow dish. (2) Heat on stove or leave in sun. (3) Liquid evaporates as vapor. (4) Solid residue remains in dish. For magnetic separation: (1) Spread mixture on flat surface. (2) Move magnet (inside plastic bag) slowly over mixture. (3) Magnetic materials stick to magnet. (4) Lift magnet away and remove bag; materials drop into separate container.
  • Filtration needs gravity or pressure; faster if you use vacuum pump in lab (not in Class 6 syllabus but good to know).
  • Evaporation is slow in cool weather; sunlight or heat speeds it up significantly—salt pans in Gujarat use sun.
  • Sedimentation time depends on particle size: sand settles in minutes, fine clay can take hours.
  • Winnowing needs a breeze; on a calm day farmers wait or use hand fans to create air current.

Key Definitions and Terms You Must Know

CBSE examiners love 2-mark 'define the following' questions. Write definitions exactly as NCERT states them—do not paraphrase. Mixture: a material made by combining two or more substances that are not chemically bonded and can be separated by physical methods (not chemical reactions). Component: each substance in a mixture (e.g. in saltwater, salt and water are the two components). Threshing: the process of beating harvested crops to separate edible seeds or grains from the inedible chaff and stalks. Winnowing: the method of separating lighter husk from heavier grains by allowing wind to blow the lighter particles away. Sieving (or sifting): the technique of separating particles of different sizes by passing the mixture through a mesh or perforated surface. Filtration: the process of separating an insoluble solid from a liquid by passing the mixture through a porous material that traps the solid. Filtrate: the clear liquid that passes through the filter during filtration. Residue: the solid material left on the filter paper after filtration. Sedimentation: the process in which heavier insoluble particles in a liquid settle down at the bottom due to gravity when left undisturbed. Decantation: pouring out the clear upper liquid layer carefully without disturbing the sediment at the bottom. Evaporation: the process by which a liquid changes into vapor due to heating, leaving behind any dissolved solid. Soluble: a substance that dissolves completely in a liquid (e.g. salt in water). Insoluble: a substance that does not dissolve and remains as particles (e.g. sand in water). Magnetic separation: using a magnet to separate magnetic materials like iron from non-magnetic materials in a mixture. Sediment: the layer of solid particles that settles at the bottom during sedimentation. Husk (or chaff): the dry outer covering of seeds that is removed during threshing and winnowing. These 16 terms cover 95 percent of definition-based questions from this chapter in the last five years of CBSE papers.
  • Filtrate vs. residue: filtrate is what you keep in water purification; residue is the waste (dirt).
  • Soluble vs. insoluble: this decides if you use evaporation (for soluble) or filtration (for insoluble).
  • Sedimentation vs. decantation: sedimentation is the waiting step; decantation is the pouring step—they go together.
  • Evaporation vs. condensation: evaporation removes liquid; condensation (not in this chapter) turns vapor back to liquid.

Decision Rules: Choosing the Right Method

This is where students lose marks—picking the wrong method. Follow this decision tree every time. Step 1: Is it solid mixed with solid, or solid mixed with liquid? If solid-solid, go to Step 2a. If solid-liquid, go to Step 2b. Step 2a (solid-solid): Are the two solids joined (like seed and husk)? Use threshing to separate them first. Are they loose but different weights? Use winnowing if one is much lighter. Are they different sizes? Use sieving with appropriate mesh. Is one magnetic (iron) and the other not? Use magnetic separation. Step 2b (solid-liquid): Is the solid dissolved (like salt in water) or just floating/suspended (like sand in water)? If dissolved, use evaporation to get the solid back. If suspended and particles are large, use filtration. If suspended and you want minimal equipment, use sedimentation plus decantation. Step 3: Can you combine methods? Often yes. Example: To separate a mixture of sand, salt, and iron filings: (i) use magnet to remove iron filings first; (ii) add water to dissolve salt; (iii) filter to separate sand (residue) from saltwater (filtrate); (iv) evaporate filtrate to get salt crystals. Four methods in sequence. In the 2023 CBSE paper, one 3-mark question asked exactly this—students who knew the sequence scored full marks; others got 1 out of 3. Practice combination problems from NCERT exercises 9.1 and 9.2.
  • If the question says 'tea leaves in tea,' answer is filtration using a strainer (a type of sieve with fine mesh).
  • If it says 'sugar in water,' evaporation is the method to recover sugar crystals—filtration will not work.
  • If it says 'chalk powder in water,' sedimentation or filtration both work; sedimentation is cheaper and traditional.
  • If it says 'grain and husk,' threshing first, then winnowing—two steps, not one.

Common Mistakes and How to Avoid Them

Every year students make the same errors. Mistake 1: Writing 'filtration' for saltwater. Wrong—salt is dissolved, filtration only removes undissolved particles. Correct: evaporation. Mistake 2: Confusing sieving and winnowing. Sieving separates by size using a mesh. Winnowing separates by weight using air current. Both work on solids, but the principle is different. Mistake 3: Saying 'evaporation separates water from sand.' Wrong again—sand does not dissolve, so evaporation would just dry the sand; you would not recover pure water. For sand and water, use filtration or sedimentation. Mistake 4: Forgetting that decantation follows sedimentation. You cannot decant unless you have let the mixture settle first. Mistake 5: Thinking magnetic separation works on all metals. It works only on magnetic materials like iron, steel, nickel, cobalt. Copper, aluminum, gold are not magnetic. Mistake 6: Drawing filtration diagram without labeling funnel, filter paper, residue, filtrate, and beaker. CBSE marking scheme awards 0.5 mark per correct label. Mistake 7: In the method name, writing 'evaporating' (verb) instead of 'evaporation' (noun). Be precise with terminology. Mistake 8: Claiming hand-picking is a standard method taught in Chapter 9—it is mentioned in passing but NCERT focuses on the seven methods listed. Stick to NCERT language in answers.
  • In diagram questions, use a ruler and pencil—freehand sketches lose marks for neatness.
  • Label every part clearly with arrows pointing exactly to the component, not floating in space.
  • If the question is worth 3 marks, write three distinct points—one-word answers will not fetch full credit.
  • Underline or bold the method name in your answer so the examiner sees it immediately.

Solved Example 1: Tea Strainer Problem

Question: Your mother makes tea by boiling water, tea leaves, milk, and sugar together. She then pours it through a tea strainer into cups. (a) Name the method of separation used. (b) What is the residue and what is the filtrate? (c) Why does this method work? Solution: (a) The method is filtration. A tea strainer is a fine sieve or mesh filter that allows liquid to pass through but traps solid tea leaves. (b) Residue: tea leaves left in the strainer. Filtrate: the liquid tea (mix of water, milk, dissolved sugar) collected in the cup. (c) This method works because tea leaves are insoluble solids much larger than the strainer holes, so they cannot pass through. The liquid and dissolved sugar molecules are tiny enough to flow through the mesh. Note: students sometimes write 'sieving' here—that is acceptable because a strainer is a type of sieve, but the NCERT term is filtration when separating solid from liquid. Marks: 1+1+1 = 3 marks total.

Solved Example 2: Farmer's Harvest Sequence

Question: A wheat farmer harvests his crop. The wheat plants are dried in the sun for a week. Describe the two methods he will use next to obtain clean wheat grains ready for selling. Solution: Step 1—Threshing: The dried wheat plants (stalks with grain heads) are spread on a hard thawing floor or fed into a threshing machine. The plants are beaten with sticks or the machine drum rotates at high speed, hitting the plants. This impact loosens the wheat grains from the stalks and breaks up the husk (chaff). The farmer now has a mixture of wheat grains, broken husk pieces, and small stalk fragments all roughly the same size. Step 2—Winnowing: The farmer takes this mixture and either tosses it into the air on a windy day or pours it slowly in front of a motorized fan. The moving air blows away the light husk and stalk pieces, which fly several meters away. The heavier wheat grains fall straight down into a basket or onto a clean mat below. After winnowing, the farmer has clean grains ready for the market. This two-step process has been used for thousands of years in India and remains the most economical method for small and medium farms. Marks: 3 marks (1.5 per method if described correctly).

Solved Example 3: Separating Sand, Salt, and Iron Filings

Question: You have a mixture of sand, salt, and iron filings. Describe a series of steps to separate all three components and collect each one separately. Solution: Step 1—Magnetic Separation: Wrap a bar magnet in a thin plastic bag or paper. Move it slowly over the mixture. Iron filings are magnetic and will stick to the magnet through the bag. Lift the magnet away and remove the bag; the iron filings drop into a separate container. Now you have a mixture of sand and salt left. Step 2—Dissolving: Add water to the sand-salt mixture and stir well. Salt is soluble in water and dissolves completely, forming a saltwater solution. Sand is insoluble and remains as solid particles in the water. Step 3—Filtration: Pour the sand-saltwater mixture through a filter paper placed in a funnel over a beaker. Sand (residue) stays on the filter paper. Saltwater (filtrate) drips into the beaker below. Remove the filter paper and let the sand dry—you have pure sand. Step 4—Evaporation: Heat the saltwater in the beaker on a stove or leave it in the sun until all the water evaporates. Salt crystals are left behind in the beaker—you have pure salt. Final result: three containers with iron filings, sand, and salt, each separated and pure. This question is worth 5 marks in board exams—1 mark per step plus 1 for logical sequence. Always write steps in order and explain why each method works.

Memory Tricks and Mnemonics

Remembering seven methods is easy if you use a mnemonic. Try this sentence: 'The Wise Student Finds Science Discussions Enjoyable Mostly.' Each first letter matches a method—Threshing, Winnowing, Sieving, Filtration, Sedimentation, Decantation, Evaporation, Magnetic separation. Another trick for solid-liquid separation: if it dissolves, EVaporate; if it does Not dissolve, FiLter (EVNFL). For solid-solid separation: different Size—Sieve; different Weight—Winnow; different Magnetic property—Magnet (SWM). To remember filtration parts: 'Residue Remains, Filtrate Flows' (both start with same letter). For the harvest sequence: 'Thresh first, Then Winnow' (alphabetical T before W). When revising the night before exam, close your eyes and visualize your kitchen or a farm—imagine your mother sieving flour (sieving), draining rice water (decantation), boiling milk until cream forms (evaporation). Real-life images stick better than abstract definitions. Make flashcards: one side has a mixture (e.g. 'muddy water'), flip side has the method ('filtration or sedimentation + decantation'). Quiz yourself daily for five minutes. Within three days these become automatic.
  • Mnemonic for mixture types: 'Solid-Solid needs Size or Wind or Magnet; Solid-Liquid needs Filter or Settle or Heat.'
  • Rhyme: 'Heavy things settle down (sedimentation), light things fly around (winnowing).'
  • Acronym for filtration setup: FRRB—Funnel, Residue, Filtrate, Beaker (top to bottom in the diagram).
  • Number trick: 3 methods use gravity (sedimentation, winnowing, sieving), 2 use heat/energy (threshing, evaporation), 2 use physical barriers (filtration, magnetic field).

One-Glance Revision Box for Last-Minute Prep

Read this box 5 minutes before entering the exam hall. (1) Threshing = beat dried crops to free seeds. (2) Winnowing = wind blows away light husk. (3) Sieving = mesh separates by size. (4) Filtration = liquid passes through porous barrier, solid stays. Filtrate = liquid you collect; Residue = solid left behind. (5) Sedimentation = heavy particles sink when left undisturbed. (6) Decantation = pour clear liquid off the top after sedimentation. (7) Evaporation = heat liquid until it turns to vapor, dissolved solid remains. (8) Magnetic separation = magnet pulls iron/steel from mixture. Key decision: Dissolved solid? → Evaporation. Undissolved solid in liquid? → Filtration or Sedimentation. Different size solids? → Sieving. Different weight solids? → Winnowing. One solid magnetic? → Magnetic separation. Seeds stuck to husk? → Threshing first. Common traps: saltwater → evaporation NOT filtration; sand in water → filtration NOT evaporation; grain + husk → threshing THEN winnowing, not one method. Diagram labels for filtration: funnel, filter paper, mixture being poured, residue on paper, filtrate dripping, beaker below. For sieving: sieve/mesh, larger particles on top, smaller particles falling through. Remember NCERT language: use terms like 'insoluble,' 'filtrate,' 'residue,' 'sediment' exactly as taught. Write method name first in every answer so you get credit even if explanation is weak. Time management: definition questions 1 minute each, diagram 3 minutes, process description 4 minutes, combination problem 5 minutes. If stuck, skip and return—never leave a question blank because even partial answers earn marks in CBSE.
  • Fastest method on paper: write method name, draw a small labeled diagram, write two-line explanation—covers all mark distribution.
  • If question says 'give reason,' write 'because [property of material] and [how method exploits that property].'
  • In 3-mark questions, split into three clear points using (a), (b), (c) or bullet points—easier for examiner to award marks.
  • Underlining: underline every method name and every technical term (filtrate, residue, sediment, soluble, insoluble) in your answer.

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  • Photo-upload feature: click your NCERT exercise page and get solutions for all questions on that page in one go.
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  • Progress tracker: the AI notes which methods you confuse often and gives you extra practice problems on those.
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Frequently asked questions

Why is evaporation not used to separate sand from water?+
Sand is insoluble—it does not dissolve in water, so evaporation would only dry out the sand and leave it as wet sand, then dry sand. You would not recover pure water. Use filtration or sedimentation + decantation to separate insoluble sand from water; evaporation works only for dissolved substances like salt or sugar.
Can I use filtration to get salt back from saltwater?+
No. Filtration traps only insoluble solid particles that do not dissolve. Salt dissolves completely in water, so salt molecules pass through the filter paper along with water. To recover salt from saltwater, you must use evaporation, which turns water into vapor and leaves salt crystals behind.
What is the difference between sieving and winnowing?+
Sieving separates solids by particle size using a mesh or perforated surface—smaller particles fall through, larger stay on top. Winnowing separates solids by weight using wind or air current—lighter particles blow away, heavier fall straight down. Both are for solid-solid mixtures but use different properties (size vs. weight).
Do I need to do sedimentation before decantation, or can I do decantation alone?+
You must do sedimentation first. Sedimentation is the process of letting heavy particles settle to the bottom when the mixture is left undisturbed. Only after particles have settled can you decant (pour off) the clear liquid from the top. Decantation without sedimentation means you pour out cloudy liquid with particles still floating—you achieve no separation.
Why does a tea strainer work as a filter?+
A tea strainer has tiny holes that allow liquid tea (water, milk, dissolved sugar) to pass through but block solid tea leaves because the leaves are much larger than the holes. This is filtration—separating insoluble solid from liquid using a porous barrier. NCERT accepts both 'filtration' and 'sieving' as correct answers for tea strainer questions.
Can magnetic separation remove all metals from a mixture?+
No. Magnetic separation works only on magnetic metals like iron, steel, nickel, and cobalt. Non-magnetic metals such as copper, aluminum, gold, silver, and zinc will not stick to a magnet and remain in the mixture. Always check if the metal in the question is magnetic before choosing this method.
In the exam, should I draw diagrams for every method or only when asked?+
Draw a labeled diagram only if the question explicitly says 'draw and label' or 'with the help of a diagram.' If the question asks 'describe the method,' write the process in points and skip the diagram to save time. However, a small neat diagram often earns you an extra 0.5 bonus mark if space and time permit.
How do I separate a mixture of sugar and salt, both of which dissolve in water?+
This is a Class 6 challenge question. Because both dissolve, you cannot use filtration or sedimentation. One method is to use the difference in solubility: salt is much more soluble in cold water than sugar. Add minimal water to dissolve only salt, filter out undissolved sugar, then evaporate the saltwater to get salt. This is advanced and not in NCERT Chapter 9—stick to NCERT methods in exams unless the question provides hints.
What is the correct order: threshing or winnowing first?+
Always threshing first, then winnowing. Threshing separates seeds from stalks and breaks up husk. After threshing, you have a mixture of seeds and broken husk pieces of similar size. Winnowing then uses wind to blow away the lighter husk, leaving clean seeds. If you try to winnow before threshing, the seeds are still attached to stalks—wind cannot separate them.
How much time should I spend on Chapter 9 questions in the exam?+
CBSE typically allocates 6–8 marks to this chapter in the Class 6 final (out of 80 total). Budget roughly 10–12 minutes: 2 minutes for definitions, 3 minutes for a diagram, 3 minutes for describing a method, and 3 minutes for a reasoning or combination question. Practice past papers with a timer so you stay within this limit and have time for other chapters.

Related resources

Important Questions: CBSE Class 6 Science Chapter 9 Methods of Separation in Everyday LifeCBSE Class 6 Science Chapter 9 Methods of Separation in Everyday Life Worksheet with AnswersNCERT Solutions for CBSE Class 6 Science Chapter 9: Methods of Separation in Everyday LifeCBSE Class 6 Science Chapter 9 Methods of Separation in Everyday Life — NotesAI Tutor for Class 6: The Smart Alternative to TuitionAI Tutor for Class 6 Maths: Learn Faster with Instant HelpOnline Class 9 Science Tutor in Mumbai – 24/7 CBSE-Aligned AI CoachingClass 9 Mathematics Chapter 2 Polynomials — Formulas & Key Points

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