NCERT Solutions Curiosity Chapter 9 –181Projects, play and thinking like a scientist — Learning further

Book page 180 Updated on2026-09-05

Q1.

Fun with parents: We are proud of our Indian heritage. Under supervision of your elders, try to prepare some herbal remedies using various parts of plants. For example—tulsi kadha. Which methods of separation will you use while preparing herbal kadha?

Answer

Methods of separation used while making tulsi kadha:

Step in making kadha	Method of separation
Picking healthy tulsi leaves and removing the damaged ones, stalks and dust	Handpicking
Drying herbs, roots or leaves in the shade before storing	Evaporation (of the water in them)
Powdering dry ginger or pepper and sifting out the coarse bits	Sieving
Letting the boiled kadha stand so the heavier bits sink	Sedimentation
Pouring the clear kadha into a cup, leaving the residue in the pan	Decantation
Straining the kadha through a chhanni or a muslin cloth	Filtration
The steam that condenses on the lid and drips back	Condensation

Sample answer — a simple tulsi kadha (make it with an adult): Boil 1 glass of water. Add 8–10 washed tulsi leaves, 2 crushed black peppercorns, a small piece of crushed ginger and 2 crushed cloves. Keep it covered and simmer until it reduces to about half a glass. Strain it through a tea strainer into a cup, add a little honey or gud after it has cooled a bit, and drink warm. The main separation method here is filtration.

Why the herbs are dried in the shade, not in bright sun: as the book’s ‘Do you know?’ box explains, shade drying lets the excess water evaporate slowly while keeping the useful part of the medicine intact. Strong sunlight can destroy the delicate substances in the leaves.

Q2.

Stage play: Imagine you and your friend are Malli and Valli. Write dialogues of a play presenting their entire ‘Bharat ki Yatra’, highlighting the different methods of separation of substances that they observed. Enact the play in your school assembly.

Answer

What a good script must contain: five scenes for the five halts, each one naming the method, showing it being done and stating which property it uses; a narrator to move the play along; and a short closing that says why we separate substances.

Scene	Place	Methods to show
1	Nani’s house, Haryana	Handpicking, threshing, winnowing, sieving
2	Sabarmati, Ahmedabad	Evaporation (salt from seawater); the Dandi March
3	Dada’s house, Puducherry	Sedimentation, decantation, filtration
4	A dhaba in Bhopal	Churning
5	Bua’s house, Shillong	Magnetic separation

Sample answer — an opening you can build on:

Narrator: Summer holidays, and a family is off on a Bharat ki Yatra. First stop — Haryana.
Valli: Nani, why is everyone picking through the grain?
Nani: We are taking out the small stones, beta, so the grain is fit for cooking. We do it by hand — that is handpicking.
Malli: But the husk is so much more than the stones! Will you pick all of that by hand too?
Mama (laughing): No. For that we call the wind. (He lifts a soop and lets the grain fall.)
Valli: Look! The grain drops straight down and the husk flies off!
Mama: Because the husk is lighter. That is winnowing.
Narrator: One property, one method. Now to Ahmedabad …

Tip for the performance: use real props — a soop, a chalni, a tea strainer, a magnet and a bowl of sawdust with nails. The audience believes what it can see happening, and the science is remembered far longer.

Q3.

Group activity: Observe and list separation methods you employed and noticed in your surroundings throughout a week. Explain the reasons behind using these methods and compile the ones you utilised or observed the most. Compare your observations with your group members.

Answer

How to do it properly: keep a small diary for seven days. Each time you see a mixture being separated, write down four things — where, what was separated, which method, and why that method was chosen. Then count how often each method appears.

Day / Place	What was separated	Method	Why that method
Mon — kitchen	Stones from dal	Handpicking	Few stones, easily seen and picked
Mon — kitchen	Bran from atta	Sieving	Bran is bigger than the flour particles
Tue — tea time	Tea leaves from tea	Filtration	Complete removal is wanted
Wed — washing rice	Dirt and husk from rice	Decantation	Dirt floats or settles; water is poured off
Thu — after rain	Puddle drying up	Evaporation	Sun and wind take the water away
Fri — building site	Pebbles from sand	Sieving	Clear size difference
Sat — home	Butter from curd	Churning	Butter is lighter and floats
Sun — scrap shop	Iron pieces from waste	Magnetic separation	Only iron is attracted

What you will find: almost every group finds that handpicking, sieving and filtration are the commonest, because most household mixtures are solid–solid or solid–liquid and the components differ in size. Methods needing heat, such as evaporation, are seen far less often at home.

Compare and discuss: a classmate whose family farms will report threshing and winnowing; one who lives near the coast may report salt pans. Different surroundings, same small set of methods — that is a good discovery to end with.

Q4.

Be a stalwart of your community: Interview a ragpicker(s) and prepare a case study about the method(s) of separation he/she uses in his/her daily life. Encourage children of your community below the age of 14 to join a neighbourhood school.

Answer

How to conduct the interview: go with a teacher or a parent, ask permission first, be respectful, listen more than you speak, and thank the person afterwards. Never photograph anyone without asking.

Questions worth asking:

What kinds of waste do you collect and separate?
How do you decide which pile a thing belongs to?
Do you use any tool — a magnet, a sieve, a hook, gloves?
Which is the hardest material to separate, and why?
What happens to each pile after you sell it?
What difficulties do you face in this work?

Waste sorted	Separated on the basis of	Method
Paper, plastic, glass, cloth	Appearance and feel of the material	Handpicking (sorting)
Iron and steel scrap	Attraction to a magnet	Magnetic separation
Aluminium cans vs iron cans	Only iron sticks to the magnet	Magnetic separation
Plastic bottles vs sand and grit	Plastic floats in water, grit sinks	Decantation / flotation
Fine dust from mixed waste	Particle size	Sieving

What the case study should conclude: ragpickers do skilled separation work every day, mostly by handpicking, and their work is the first step of recycling. It keeps enormous quantities of material out of landfills. They deserve safety equipment — gloves, shoes and masks — and respect.

The second half of the task matters as much: find out whether any child in the family is out of school, tell the parents about the nearest government school, mid-day meal and free books, and inform your class teacher. Education for every child under 14 is a right under the Right to Education Act.

Q5.

Be a reporter: (i) Gather newspaper clippings and articles related to various methods of separation implemented in your society, such as in agricultural fields or at construction sites. (ii) Conduct interviews with local farmers to explore the latest agricultural separation methods that they use.

Answer

(i) Making the clippings file. Keep a scrapbook with four sections — Farming, Construction, Water and Waste and recycling. Paste each clipping and write under it: the date, the method of separation involved and the property it uses.

Kind of news item	Separation you will spot
Harvest reports, combine harvesters, mandi photos	Threshing and winnowing
Sand screening, ready-mix concrete plants	Sieving
Water treatment plants, filter distributions after a flood	Sedimentation, filtration
Salt production in Gujarat or Tamil Nadu	Evaporation
Waste segregation drives, scrap yards with crane magnets	Handpicking, magnetic separation
Oil spill clean-up at sea	Decantation / skimming

(ii) Interviewing a farmer — questions to ask:

How was the crop threshed when you were young, and how is it done now?
Do you use a thresher or a combine harvester? Is it owned, hired or shared?
Does the machine do winnowing as well? What is done with the husk?
How are the grains graded and cleaned before they go to the mandi?
How are seeds separated and sorted for the next sowing?
Which is faster and which is cheaper — the old way or the machine?

What you will learn: the principle has not changed at all — a thresher still beats the crop, and it still blows air through the falling grain. Only the muscle has changed, from a wooden log and the wind to a diesel engine and a fan. A combine harvester cuts, threshes and winnows in one pass across the field.

Q6.

Think like a scientist: You are provided with a mixture of iron nails, sand, black pepper, stones, common salt and water. Which steps will you follow to separate each component of a mixture?

Answer

Six components — so use one property at a time, and always take out the easiest first. Here is the full sequence.

Step	What to do	Method	Component obtained
1	Move a magnet over the mixture. The nails cling to it.	Magnetic separation	Iron nails
2	Pick out the stones and the black pepper by hand — both are large and easy to tell apart by colour and shape.	Handpicking	Stones and black pepper
3	Stir what is left. The salt dissolves in the water; the sand does not and settles at the bottom.	Sedimentation	Sand settled; salt in solution
4	Pour off the clear salt solution, then pass it through a filter paper to catch every last grain of sand. Dry the sand.	Decantation and filtration	Sand (as residue)
5	Heat the filtrate (or leave it in the sun) so that the water leaves as vapour.	Evaporation	Common salt
6	To keep the water as well, cool the vapour on a cold surface so that it turns back into liquid.	Condensation (distillation)	Water

Mixture
—[magnet]→ iron nails
—[handpicking]→ stones, black pepper
—[settle + filter]→ sand
—[evaporate]→ salt —[condense the vapour]→ water

Why this order and not any other:

The magnet goes first because it picks out iron and nothing else, and sharp nails are best removed before you put your fingers in.
Handpicking comes next because stones and pepper are the biggest things left; taking them out early makes everything after it easier.
Only then do we use water as a tool, because it makes use of the one property left — salt dissolves, sand does not.
Evaporation must come last, since it needs a clear solution with nothing else floating in it.

Reflection steps — fill these in your own words: “I observe that this mixture has solids of very different sizes, one metal, and one solid that vanishes in water. I wonder whether I can use water itself as a way of separating them.” The book’s hint is the key idea: a mixture of more than two components needs a combination of separation methods.

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