NCERT Solutions Curiosity Chapter 9 Interdisciplinary projects — Exploratory Projects

Book page 136 Updated on2026-09-05

Q1.

What are the good practices for maintaining oral hygiene? Try to gather information on the same from books/newspapers/conversation with elders. Prepare a report.

Answer

How to do this project: collect information from three kinds of sources — a science or health book, a newspaper or magazine article, and a conversation with elders at home. Note the source of each point. Then arrange your report under headings: Why oral hygiene matters → What to do daily → What to avoid → What our elders did → Conclusion. Two pages, with a small labelled sketch of a tooth-brushing routine, is enough.

A good report must contain: at least six specific practices, one reason for each, at least one point taken from an elder, and a clear statement of where each fact came from.

Sample answer:

Good practice	Why it helps
Brush teeth twice a day — morning and before sleeping	Removes the sticky film of food in which germs grow and cause tooth decay
Clean the tongue twice a day	The coating on the tongue is a main cause of bad smell in the mouth
Rinse the mouth with water after every meal	Washes away food bits stuck between the teeth before they can decay
Cut down on toffees, chocolates and sweet drinks, especially at night	Sugar left on the teeth is exactly what decay-causing germs feed on
Eat crunchy fruits and vegetables — guava, carrot, cucumber, apple	Chewing them cleans the teeth and increases the flow of saliva
Do not open bottle caps or bite hard nuts with the teeth	Prevents cracks and chipping
Change the toothbrush every 3 months	Bent, worn bristles no longer clean the corners
Get the teeth checked once a year	A small cavity can be filled easily; a neglected one becomes painful and costly

From my grandmother: "Till I was married I used a neem datun every morning, cleaned my tongue with a copper jibhi, and rinsed my mouth after every meal. We rarely ate sweets, and no one in our house had a decayed tooth."

Tip: end the report with one line of your own — what you have decided to change in your own routine after doing this project.

Q2.

Find out different ways to maintain a healthy digestive system. Suggest some food items that help to maintain good digestive health. Make a report and present it in class.

Answer

How to do this project: gather your points from the chapter itself (fibre, fermented food, the Charaka Samhita box), from a doctor or an elder, and from a health article. Then make two lists — habits and foods — and turn them into a five-minute class presentation with one chart paper.

A good report must contain: habits as well as foods; a reason for each; at least two examples from local Indian food; and one thing to avoid.

Sample answer — habits:

Eat meals at proper timings and do not skip them — modern nutrition science and the Charaka Samhita agree on this.
Chew food well and eat slowly (mindful eating). Digestion begins in the mouth; food swallowed in a hurry gives saliva no time to act.
Avoid overeating. A stomach filled too full cannot churn the food properly.
Drink enough water. The large intestine needs water to keep the stool soft.
Wash hands before eating and eat freshly cooked food, to keep out germs.
Be physically active — walking, cycling and play keep the gut moving.
Do not lie down straight after a heavy meal; take a short walk instead.

Sample answer — foods:

Food	How it helps
Fruits and vegetables — papaya, guava, banana, spinach, carrot	Rich in fibre and water; make the stool easier to pass
Whole grains and millets — jowar, bajra, ragi, whole wheat, brown rice	Fibre-rich; millets are also naturally gluten-free
Fermented foods — curd, buttermilk, shrikhand, kanji, pickles, gundruk, poita bhat	Help the useful bacteria of the large intestine, which break down fibre and make essential nutrients
Pulses and beans	Provide protein along with fibre
Spices used sensibly — ginger, black pepper, cumin	The Charaka Samhita notes their judicious use to enhance digestion
Plenty of plain water	Prevents hard stool and constipation

Tip: what to cut down on — too much fried food, packaged snacks, and cold drinks. They carry very little fibre and slow the gut down.

Q3.

Using coloured clay, prepare a 3-D model of the digestive system and label all parts of the digestive system using black paper strips.

Answer

How to do this project: take a stiff cardboard sheet as the base and draw a faint human outline on it. Roll and shape coloured clay for each organ, press it into place, then write the names on black paper strips in white ink and pin them beside each organ with a thread leader.

A good model must contain every part of the alimentary canal in the correct order, the two associated parts (liver and pancreas) shown pouring into the small intestine, and correct relative sizes — the small intestine must be clearly the longest and the large intestine clearly the widest.

Part to make	Shape and colour of clay	Label on the black strip
Mouth	Small open oval, pink	Mouth — teeth chew; saliva starts starch digestion
Oesophagus	Long thin rope, light pink, straight down	Food pipe (Oesophagus) — pushes food to the stomach
Stomach	J-shaped bag, deep pink or red	Stomach — churns food; digestive juice, acid and mucus
Liver	Large flat wedge, dark brown, upper right	Liver — secretes bile
Pancreas	Thin leaf shape, cream, tucked below the stomach	Pancreas — secretes pancreatic juice
Small intestine	A very long thin rope, orange, coiled tightly in the middle	Small intestine — about 6 m; digestion completed and nutrients absorbed
Large intestine	A thicker, shorter tube, purple, framing the coil like an arch	Large intestine — about 1.5 m; absorbs water and salts
Rectum	Short straight piece at the lower end	Rectum — stores the stool
Anus	Small opening at the bottom	Anus — egestion

Tip: roll the small intestine as one single long rope, not several short pieces. The whole point of the model is to show a student how astonishingly long that one tube is.

Q4.

What is air quality and AQI? Find out the effect of air quality on the respiratory systems of people working in various fields — farmers, factory workers, or street vendors.

Answer

Air quality tells us how clean or polluted the air is. AQI stands for Air Quality Index — a single number, published daily for Indian cities by the Central Pollution Control Board, that turns the amounts of the main pollutants (fine dust PM2.5 and PM10, sulphur dioxide, nitrogen dioxide, carbon monoxide and ozone) into one easy figure with a colour.

AQI value	Category	What it means for breathing
0–50	Good	Air causes little or no risk
51–100	Satisfactory	Minor breathing discomfort to a few sensitive people
101–200	Moderate	Discomfort for people with asthma or lung and heart disease
201–300	Poor	Breathing discomfort to most people on long exposure
301–400	Very poor	Respiratory illness on prolonged exposure
401–500	Severe	Affects even healthy people; serious effect on those already ill

How to do this project: note your city's AQI from a newspaper or the SAMEER app every day for a week and plot it as a bar graph. Then interview two or three working people and write down, in their own words, what they notice about their breathing.

Sample findings:

Farmers — dust while ploughing and threshing, smoke from burning crop residue, and spray from pesticides. Many report cough, sneezing, watery eyes and breathlessness during the harvest and stubble-burning weeks.
Factory workers — fine dust from stone cutting, cement, cotton mills or grinding, and chemical fumes. Long exposure damages the lungs and can lead to lasting lung disease; a good factory therefore supplies masks and exhaust fans.
Street vendors and traffic police — spend the whole day beside vehicles, breathing exhaust smoke and road dust. They commonly report a burning throat, frequent colds and headache in winter, when smoke settles low near the ground.

Tip: end with practical suggestions — a proper mask (not a thin cloth), planting trees along roads, not burning leaves or crop residue, watering dusty roads, and taking short breaks in clean air. Recall from the chapter that the nose can filter only part of the dust; the rest reaches the lungs.

Q5.

Try to read about the box-breathing technique (Fig. 9.17). What are its benefits?

Answer

Box breathing (also called square breathing) is a simple, slow breathing exercise with four equal steps — which is why the book draws it as a square (Fig. 9.17). Count four seconds for each side of the square:

Box breathing: four equal steps of four counts each, done slowly through the nose.

Benefits reported for box breathing:

Calms the mind quickly — it slows a racing heart and settles nervousness before an exam, a stage performance or a match.
Improves concentration, because counting gives the mind one simple thing to hold on to.
Makes breathing deep and regular instead of shallow and fast, so more air reaches the lower parts of the lungs.
Strengthens the diaphragm and the breathing muscles with regular practice.
Helps with sleep when done for a few minutes at bedtime.
Needs nothing at all — no equipment, no space, and it can be done sitting in a classroom.

Tip: breathe through the nose, keep the back straight, and never strain. If four counts feel long, start with three. This belongs to the same family as pranayama, which Indian traditions have used for centuries for respiratory health, relaxation and concentration.

Q6.

Both birds and mammals have lungs for breathing, but birds can fly at high altitudes where oxygen levels are low. How might their respiratory system be adapted to help them survive in such conditions?

Answer

Flying is very hard work, and the air high above the ground is thin — a given breath there carries far less oxygen. A bird's respiratory system is built to squeeze more oxygen out of less air.

Air sacs. Besides lungs, a bird has thin-walled air sacs spread through its body. They act like bellows, storing and pushing air, so the lungs are never left empty between breaths.
Fresh air flows through the lungs in one direction. In a mammal the air goes in and comes back out of the same blind sacs, so each fresh breath mixes with stale air. In a bird the air keeps moving forward, so the lung is bathed in fresh air both while breathing in and while breathing out.
Oxygen is taken up even during exhalation. Because of this one-way flow, a bird does not waste half of every breathing cycle.
Very fine, closely packed air tubes in the lung give a large surface in contact with blood, so oxygen passes into the blood quickly.
Blood that holds oxygen tightly and a fast, powerful heart carry the oxygen quickly to the flight muscles.
A high breathing rate during flight moves a large volume of air through the system.

Result: the chapter notes that "some other animals can use a larger fraction of the oxygen during respiration". Birds are exactly such animals — they take a bigger share of the oxygen out of each breath than we do. That is why bar-headed geese can fly over the Himalayas, at heights where a human being would need an oxygen cylinder.

Why it happens: flight muscles work far harder than walking muscles, so they need a great deal of energy, and energy comes from breaking down glucose with oxygen. An animal that needs more oxygen where there is less of it can survive only by improving the delivery system — which is exactly what a bird's respiratory system does.

How to explore this: read about bar-headed geese and Rüppell's vulture, and draw a simple comparison chart — mammal lung: air in and out of the same sac; bird lung: air flows through in one direction with air sacs at both ends.

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