NCERT Solutions Class 8 Science Chapter 1 Exploring the Investigative World of Science

Exploring the Investigative World of Science explains how curiosity becomes careful observation, testing and explanation.
These NCERT Solutions help students answer Chapter 1 questions on investigation, variables, experiments and everyday science.

Science in Class 8 begins with questions students can notice at home, outdoors and in the sky. A puri puffing in hot oil, a fruit turning brown, the Moon changing shape, or leaves having different forms can all become science questions. NCERT Solutions Class 8 Science Chapter 1 help students understand how curiosity becomes investigation. The chapter shows how to ask focused questions, change one condition at a time, record observations and use evidence to improve explanations for 2026-27 learning.

Key Takeaways

  • Curiosity: Science starts when students ask focused “why” and “how” questions.
  • Investigation: A good investigation uses careful observation, testing and explanation.
  • Variables: Experiments work better when one condition changes at a time.
  • Evidence: Notes, measurements and observations help improve scientific understanding.

NCERT Solutions Class 8 Science Chapter 1 Structure 2026-27

Section Textbook Focus What Students Learn
Probe and Ponder Curiosity-based questions Asking scientific questions
Investigative World Grade 8 science journey Observation, experiments and explanation
Puri Example Everyday investigation Variables, measurements and notes

Probe and Ponder

The first page of Class 8 Science Chapter 1 Exploring the Investigative World of Science asks curiosity questions. These questions train students to look at daily life like young scientists.

Q1. Why is one side of a puri thinner than the other?

Answer: One side of a puri may become thinner because steam pushes unevenly inside the dough.

When a puri enters hot oil, water in the dough changes into steam. The steam expands and pushes the two dough layers apart.

One side may stretch more because of uneven thickness, oil temperature or the way the puri enters oil.

This makes one side look thinner after puffing.

Q2. Are there more grains of sand on all beaches and deserts, or more stars in our galaxy?

Answer: This question needs estimation, not guessing.

A scientist would estimate sand grains using area, depth and grain size.

Stars can be estimated through astronomical observations.

The question shows that science often begins with measurement, comparison and evidence.

Q3. Why has nature created such a vast variety of plants and animals?

Answer: Nature has variety because living organisms adapt to different surroundings.

Plants and animals live in forests, deserts, oceans, grasslands and mountains.

Each place has different food, water, temperature and safety needs.

Over long periods, organisms develop features suited to their surroundings.

This creates biodiversity.

Q4. Write one question that makes you curious about the world.

Answer: Students can write any observation-based science question.

Example:

Why do some fruits turn brown after cutting?

This is a good science question because it can be tested through observation.

Students can compare cut fruits kept in air, water and lemon juice.

Exploring the Investigative World of Science Class 8 Questions and Answers

Exploring the Investigative World of Science Class 8 questions and answers focus on how science works. The chapter connects curiosity, observation, testing and evidence.

Q1. What does investigation in science mean?

Answer: Investigation in science means finding answers through careful observation, testing and explanation.

It starts with a question.

Then students decide what they can change, what they can keep the same and what they can observe.

The answer should come from evidence.

Q2. How is Grade 8 Science different from earlier classes?

Answer: Grade 8 Science asks students to move from wonder to investigation.

In Grade 6, students learnt that science begins with simple questions.

In Grade 7, they learnt that scientific ideas can change with deeper study.

In Grade 8, students learn how to ask focused questions and test them.

This makes students investigators, not only learners.

Q3. Why are questions important in science?

Answer: Questions are important because they guide investigation.

A good question tells students what to observe or test.

For example, “Why does dough rise?” can lead to experiments on yeast, warmth and time.

Without questions, observations may remain random.

Q4. Why should students change only one thing at a time in an experiment?

Answer: Students should change one thing at a time to identify the real cause.

If thickness, oil temperature and flour type change together, results become confusing.

A fair experiment keeps other conditions the same.

Then students can see which change caused the result.

Q5. Why is it important to record observations?

Answer: Recording observations helps students compare results accurately.

Memory can be incomplete or biased.

Notes can include time, smell, colour, shape, sound and measurements.

These records help students improve their explanation later.

Q6. Why does the textbook use root and kite symbols?

Answer: The root symbol shows a strong foundation of knowledge.

It reminds students to stay connected to observation, environment, traditions and heritage.

The kite symbol shows curiosity and imagination.

Together, they show that science needs both careful evidence and creative thinking.

Q7. What does the puri example teach about scientific investigation?

Answer: The puri example shows that science can begin in a kitchen.

Students can observe how puris puff in hot oil.

They can change thickness, flour type, oil temperature or dropping method.

They can then record whether the puri puffed, how fast it puffed and which side became thinner.

This makes an everyday event a systematic investigation.

NCERT Solutions Class 8 Science Chapter 1: Puri Puffing Experiment

NCERT Solutions for Class 8 Science Chapter 1 Exploring the Investigative World of Science should help students understand how an ordinary kitchen observation becomes a science activity. The puri example teaches variables, fair testing and observation.

Aim of the Investigation

The aim is to find what affects how a puri puffs up.

Students can test dough thickness, flour type, oil temperature or dropping method.

Things We Can Change

These are called variables.

In this experiment, variables include dough thickness, dough size, flour type, oil temperature and dropping style.

Things We Should Keep the Same

A fair test keeps most conditions unchanged.

Students may keep dough size, flour type and frying method the same when testing only oil temperature.

Things We Can Observe

Students can observe whether the puri puffs up.

They can measure the time taken to puff.

They can also note oil splatter, smell, smoke and side thickness.

Sample Observation Table

What Is Changed What Is Kept Same What Is Observed
Oil temperature Same dough size and thickness Puffing time
Dough thickness Same oil temperature Thin side formation
Flour type Same frying method Shape and puffing

What Students Learn

The puri puffing experiment class 8 example shows that simple questions can become scientific investigations.

A good investigation needs planning, controlled changes and honest observations.

Class 8 Science Chapter 1 Curiosity: Chapter Ideas Students Should Know

Class 8 Science Chapter 1 Curiosity introduces the learning journey for the year. It links microbes, health, electricity, force, pressure, light, Moon phases, ecosystems and climate.

Microbes and Health

The book begins by looking at tiny organisms in water and around us.

Some microbes help digestion and medicine production.

Others can cause infections.

Electricity and Forces

Students later study electric current and its effects.

They also learn how forces make objects speed up, slow down or change direction.

Pressure and Weather

Force and pressure help explain air movement.

Small pressure differences create breezes.

Stronger pressure differences can create cyclones.

Materials and Particles

Everything around us is made of tiny particles.

Particles behave differently in solids, liquids and gases.

Light and Vision

Light reflects from mirrors and bends through lenses.

This helps explain spoons, corrective glasses and optical devices.

Moon, Calendars and Earth

Moon phases helped humans create calendars.

The chapter connects sky observations with daily routines on Earth.

Ecosystems and Climate

Living beings depend on air, water, sunlight and other organisms.

The book ends by connecting science with climate challenges.

Investigative World of Science Class 8: How to Answer Chapter 1 Questions

Investigative world of science class 8 answers should sound like scientific reasoning. Students should explain what they observed and how they would test it.

Start With the Question

A good answer begins with the exact question being investigated.

Example: Does oil temperature affect how fast a puri puffs?

Mention the Variable

Write what you will change in the experiment.

Example: Oil temperature will be changed.

Keep Other Conditions Same

Mention at least two things kept constant.

Example: Dough size and flour type will remain the same.

Record the Observation

Write what will be observed or measured.

Example: Time taken to puff will be measured in seconds.

Draw a Conclusion

The conclusion should come from observations.

Example: If hotter oil makes puris puff faster, temperature affects puffing.

NCERT Solutions Class 8 Science Exploring the Investigative World of Science: Chapter Value

NCERT Solutions Class 8 Science Exploring the Investigative World of Science help students understand the process of learning science. The chapter is less about memorising facts and more about thinking clearly.

Curiosity Becomes a Question

A student may first notice something simple.

Then that observation becomes a focused question.

A Question Becomes a Test

A focused question helps students decide what to change.

It also helps them decide what to observe.

A Test Gives Evidence

Evidence may come from measurements, notes or repeated observations.

This makes the answer stronger than a guess.

Evidence Improves Understanding

Scientific understanding can change when new evidence appears.

This is why investigation is an ongoing process.

Useful Links for Class 8 Science

Section Useful Links
NCERT Solutions NCERT Solutions for Class 8 Science
Revision Notes CBSE Class 8 Science Revision Notes
Important Questions CBSE Important Questions Class 8 Science
Syllabus CBSE Class 8 Science Syllabus
Sample Papers CBSE Sample Papers for Class 8 Science

Q.1 Select the correct word from the following list and fill in the blanks.
float, water, crop, nutrients, preparation
(a) The same kind of plants grown and cultivated on a large scale at a place is called _______.
(b) The first step before growing crops is _____ of the soil.
(c) Damaged seeds would ______ on top of water.
(d) For growing a crop, sufficient sunlight and _____ and________ from the soil are essential.

Ans-

(a) Crop
(b) preparation
(c) float
(d) water, nutrients

Q.2 Match items in column A with those in column B.

A

B
(i) Kharif crops (a) Food for cattle
(ii) Rabi crops (b) Urea and super phosphate
(iii) Chemical fertlilisers (c) Animal excreta, cow dung, urine and plant waste
(iv) Organic manure (d) Wheat, gram, pea
(e) Paddy and maize

 

Ans-

A

B
(i) Kharif crops (e) Paddy and maize
(ii) Rabi crops (d) Wheat, gram, pea
(iii) Chemical fertlilisers (b) Urea and super phosphate
(iv) Organic manure (c) Animal excreta, cow dung, urine and plant waste

Q.3 Give two examples of each.
(a) Kharif crop
(b) Rabi crop

Ans-

(a) Two examples of Kharif crop are paddy and maize.
(b) Two examples of Rabi crop are wheat and gram.

Q.4 Write a paragraph in your own words on each of the following.
(a) Preparation of soil
(b) Sowing
(c) Weeding
(d) Threshing

Ans-

(a) Preparation of soil: Before growing a crop, a farmer first prepares the soil of the field. During preparation, he turns the soil with the help of a plough or a cultivator and loosens it. Loosening of soil allows the new germinating roots of the plants to penetrate deep into the soil. The loose soil also facilitates easy breathing to the roots even when they go deep into the soil. The loosened soil helps in the growth of earthworms and microbes present in the soil which further turn and loosen the soil and add humus to it. Turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients.

(b) Sowing: After soil preparation, the farmer’s next job is to sow the seeds. First, good quality and high yielding seeds are selected. Seeds are sown with the help of a tool called seed drill. This tool facilitates the sowing of seeds uniformly at proper distances and depths and saves time and labour. It ensures that seeds get covered by the soil after sowing. This prevents damage caused by birds.

(c) Weeding: The undesirable plants that grow naturally along with the main crop planted are called weeds. These weeds compete with the main crop plant for water, nutrients, sunshine and space. Weeds can be controlled by weeding. Weeding is the removal of weeds from the field. Weeding can be done by tilling and by using weedicides. Some weeds interfere even in harvesting and may be poisonous for animals and human beings.

(d) Threshing: After harvesting a crop, its grain seeds need to be separated from the chaff. This process of separation of grain seeds from chaff is called threshing. This is done with the help of a machine called combine which is in fact a combined harvester and a thresher.

Q.5 Explain how fertlisers are different from manure.

Ans-

Fertiliser Manure
It is a chemical substance which is rich in particular nutrients. It is natural substance aquired by the decompostion of organic waste such as cattle dung, human waste and plant residues.
It is decreases the soil fertility. It is increase the fertility of soil by replenishing the nutrients.
It does not provide any humus to the soil. It provides a lot of humus to the soil.
It is very rich in nutrients like nitrogen, phosphorus and pottasium. It is relatively less rich in plant nutrients.
It is responsible for soil and water pollution. It doesnot cause soil and water pollution.

Q.6 What is irrigation? Describe two methods of irrigation which conserve water.

Ans-

Irrigation is a process by which water is supplied to crops. The time and frequency of irrigation depends on the seasons, crops and soil types.

Two methods of irrigation that help in conservation of water are:

  • Sprinkler system: In this system, perpendicular pipes with rotating nozzles on top are joined to the main pipe at regular intervals. With the help of a pump, water is allowed to flow through main pipe under high pressure. From the main pipes, the water escapes outside through the rotating nozzles. This system works efficiently in sandy soil where sufficient water is not available.
  • Drip irrigation: In this system, water is dropped at the root of the plants, drop by drop. Water is not wasted in this type of irrigation and this method is used for watering fruit plants and gardens.

Q.7 If wheat is sown in the kharif season, what would happen? Discuss.

Ans-

If wheat is sown in the kharif season (from June to October), it has to face adverse climatic conditions and the entire wheat crop might get destroyed. Wheat is a rabi crop. Therefore, it requires low temperature, less humidity, less water and moderate sunshine. But if it is sown in kharif season, it would receive lot of water, excess temperature, and humidity. These climatic conditions would not favour the growth of the crop.

Q.8 Explain how soil gets affected by the continuous plantation of crops in a field.

Ans-

Continuous plantation of crops in a field causes depletion of certain nutrients like phosphorus, nitrogen and potassium etc. Plants are depended on these nutrients for their proper growth and functioning. Depletion of these nutrients from the soil would directly affect the yield of the crops sown in the depleted soil.

Q.9 What are weeds? How can we control them?

Ans-

The undesirable plants that grow naturally along with the main crop are called weeds. These weeds compete with the main crop plant for water, nutrients, sunshine and space. Weeds can be controlled by weeding. Weeding is the removal of weeds from the field.

Weeding can be done by:

Tilling: In this method, the weeds are either manually uprooted or cut from soil. The uprooted and cut weeds are then left in the field so that they would decay and act as the manure.

Using Weedicides: In this method, certain chemicals called weedicides such as 2, 4-D are sprayed over the fields to kill the weeds. Weedicides are used during the vegetative growth of weeds.

Q.10 Arrange the following boxes in proper order to make a flow chart of sugarcane crop production

Ans-

Q.11 Complete the following word puzzle with the help of clues given below.
Down
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.

Across
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from chaff.

Ans-

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FAQs (Frequently Asked Questions)

Exploring the Investigative World of Science is about how curiosity becomes investigation. It teaches students to ask questions, observe carefully, test ideas and use evidence.

Systematic investigation means testing a question in an organised way. It includes changing one condition, keeping others the same and recording observations.

A puri puffs up because water in the dough changes into steam. The steam expands and pushes the dough layers apart.

Variables are things that can change in an experiment. In the puri experiment, thickness, flour type and oil temperature are variables.

Writing observations helps students compare results correctly. It also helps them support conclusions with evidence instead of guesses.