Question Bank — Exploring the Investigative World of Science

NCERT Class 8 Science · Chapter 1 · CBSE Board Pattern

Class 8 Science Chapter 1 Question Bank CBSE Board Pattern

Section A — MCQs (10 questions, 1 mark each)

  1. Which of the following best describes the role of the ‘root’ symbol on the left-hand pages of the textbook?
    (a) It represents the freedom to explore new ideas
    (b) It symbolises the deep foundation of careful observation and knowledge
    (c) It indicates the chapters on plants and ecosystems
    (d) It shows the connection between Earth and the Moon

  2. In the context of investigating why a puri puffs up, changing the temperature of the oil while keeping the thickness of the dough the same is an example of:
    (a) Changing the dependent variable
    (b) Changing only the independent variable
    (c) Changing multiple variables at once
    (d) Ignoring observation

  3. Assertion (A): Science begins with simple “Why?” and “How?” questions about the world.
    Reason (R): In Grade 8, students are expected to move beyond simple questions to focused questions and design simple experiments.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

  4. The kite symbol on the right-hand pages reminds us that:
    (a) Scientific ideas must remain grounded only in tradition
    (b) Curiosity must be allowed to explore the unknown while staying connected to observation
    (c) All experiments must be done in a laboratory
    (d) Calendars are based only on solar observations

  5. Which of the following is not listed in the chapter as something that can be controlled while investigating the puffing of puri?
    (a) Thickness of the rolled dough
    (b) Type of flour used
    (c) The colour of the oil
    (d) Temperature of the oil

  6. Assertion (A): Systematic investigation requires changing only one factor at a time while keeping other conditions the same.
    Reason (R): This helps to clearly understand which change is responsible for the observed difference.
    (a) Both A and R are true and R is the correct explanation of A.
    (b) Both A and R are true but R is not the correct explanation of A.
    (c) A is true but R is false.
    (d) A is false but R is true.

  7. The chapter states that even the simple observation of a puri puffing up:
    (a) Is completely understood by all scientists
    (b) Is not yet fully understood by scientists
    (c) Can only be studied in a laboratory
    (d) Has no connection with scientific investigation

  8. According to the chapter, calendars on Earth are linked to:
    (a) Only the motion of the Sun
    (b) Careful observations of sunrises, sunsets and lunar cycles
    (c) The movement of artificial satellites
    (d) The heating effect of electric current

  9. The chapter describes investigation in science as a balance between:
    (a) Using only laboratory equipment and ignoring everyday observations
    (b) Solid ground of careful observation and freedom of creative thinking
    (c) Studying only living organisms and ignoring non-living materials
    (d) Memorising facts and avoiding questions

  10. Which of the following is an example of an observable or measurable outcome mentioned for the puri experiment?
    (a) The smell of the kitchen
    (b) Whether the puri puffs up (yes/no) or the time taken to puff up
    (c) The brand of the stove used
    (d) The number of people eating the puri

Section B — Very Short Answer (6 questions, 2 marks each)

  1. What does the chapter mean by “focused questions” in scientific investigation? Give one example from the puri experiment.
  2. State two things that can be changed (controlled) and two things that can be observed when investigating why one side of a puri is thinner than the other.
  3. Why does the chapter suggest keeping notes of everything sensed during an experiment?
  4. How does the chapter connect the shrinking bright part of the Moon after Purnima with scientific investigation?
  5. What is the importance of changing only one factor at a time during an experiment, as explained in the chapter?
  6. Mention any two real-life situations (other than the puri) given in the chapter where science begins with everyday curiosity.

Section C — Short Answer (5 questions, 3 marks each)

  1. Explain, with the help of the puri example, how a simple kitchen observation can be turned into a systematic scientific investigation.
  2. Describe the two symbols (root and kite) used in the textbook and explain how they together represent the process of scientific investigation.
  3. “Science is everywhere and does not require a fancy laboratory.” Justify this statement using ideas from the chapter with one example.
  4. How does the chapter show that careful observation of the Moon’s phases helped humans develop calendars? What does this tell us about the nature of scientific investigation?
  5. List three ways in which the chapter suggests recording or measuring the outcome of an experiment on puri puffing.

Section D — Long Answer (3 questions, 5 marks each)

  1. Describe the complete process of investigating the puffing of puri as explained in the chapter. Include the steps of asking a scientific question, identifying what can be changed and what can be observed, and the importance of systematic changes. (No diagram required)
  2. “Investigation in science works best when we balance careful observation with creative thinking.” Explain this statement using at least three examples or ideas from the chapter.
  3. Draw a neat labelled diagram showing a possible experimental setup to investigate the effect of oil temperature on the puffing of puri. Label the following: dough circle, oil container, thermometer (or temperature indicator), and any variable being kept constant. Write one observation that could be recorded and what it would indicate.

Section E — Case/Source-Based (2 questions, 4 marks each)

Case 1

A student wants to find out whether the way the dough is dropped into hot oil affects how a puri puffs up. She prepares circles of dough of the same thickness and size. She drops some vertically and slides others at an angle into oil of the same temperature. She notes the time taken for each puri to puff up and whether it puffs evenly.

25.1 Identify the independent variable in this investigation. (1)
25.2 Identify one variable that has been kept constant. (1)
25.3 Suggest one more observation (other than time) that the student could record. (1)
25.4 Why is it important that the dough circles are of the same thickness? (1)

Case 2

The chapter mentions that watching the periodic cycles of the Moon’s phases allowed humans to create the first calendars by combining observations of sunrises, sunsets and lunar cycles.

26.1 What does this example tell us about the starting point of scientific investigation? (1)
26.2 Name one other phenomenon mentioned in the chapter that also depends on careful, repeated observation. (1)
26.3 How is this example similar to investigating the puri in terms of the method used? (1)
26.4 Why might such observations lead to new questions even after an answer is found? (1)

Section F — HOTS and Application (4 questions, 3 marks each)

  1. Predict-and-justify: What would happen if a student changed both the thickness of the dough and the temperature of the oil at the same time while testing puri puffing? Would it be possible to clearly conclude which factor caused the difference? Justify your answer using ideas from the chapter.
  2. Analyse an anomalous observation: Suppose during a puri experiment, one puri puffs up much faster than others even though all conditions appear the same. According to the chapter’s approach to investigation, what should the student do next and why?
  3. Apply to an unfamiliar real-life situation: A cook notices that phulkas swell differently when placed directly on the flame compared to puris fried in oil. Using the investigative approach described in the chapter, suggest two questions the cook could ask and one factor that could be changed to investigate the difference.
  4. Compare two situations: Situation X: A student changes only the type of flour while keeping dough thickness and oil temperature the same. Situation Y: Another student changes both flour type and oil temperature together. Which situation allows a clearer conclusion about the effect of flour type? Justify using the chapter’s ideas on systematic investigation.
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Section A

  1. (b)
  2. (b)
  3. (a)
  4. (b)
  5. (c)
  6. (a)
  7. (b)
  8. (b)
  9. (b)
  10. (b)

Section B (Marking: 1 mark for correct point + 1 mark for brief explanation/example)
11. Focused questions are specific and testable (1); e.g., “Does oil temperature affect puffing time?” (1)
12. Change: thickness of dough, type of flour (1); Observe: whether it puffs (yes/no), time taken (1)
13. Notes help remember observations and identify patterns for further questions (2)
14. Both require careful, repeated observation to understand patterns (2)
15. Allows clear link between the changed factor and the result (2)
16. Why dough rises; whether the world is getting warmer (2)

Section C (1 mark each for three relevant points)
17. Start with question → identify variables → change one at a time → record observations (3)
18. Root = grounded observation (1); Kite = soaring curiosity (1); Together show balanced investigation (1)
19. Kitchen example of puri (1); no fancy lab needed (1); curiosity + observation sufficient (1)
20. Repeated observation of phases → first calendars (2); shows science grows from observation (1)
21. Yes/no puffing, time taken, thickness of puffed side (3)

Section D

  1. Question → variables → one change at a time → record → new questions (5 marks: 1 each for steps)
  2. Any three valid examples (puri, Moon, weather, health) with explanation (5)
  3. Diagram with 4 correct labels (3); one valid observation and its indication (2)

Section E

25.1 Way of dropping dough (1)
25.2 Thickness/size of dough or oil temperature (1)
25.3 Evenness of puffing / height of puff (1)
25.4 To ensure thickness does not affect the result (1)
26.1 Science starts with careful, repeated observation (1)
26.2 Puri puffing / weather patterns / Moon phases (1)
26.3 Both use systematic observation to find patterns (1)
26.4 Each answer raises new questions (1)

Section F

  1. Cannot conclude clearly because two variables changed together (2); chapter stresses one change at a time (1)
  2. Repeat the trial / check for unnoticed difference / note the anomaly (2); systematic investigation requires verification (1)
  3. Two testable questions (2); one controllable factor (1)
  4. Situation X allows clearer conclusion (1); only one variable changed (2)
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All questions are answerable from the NCERT chapter text. Reviewed by GFIS faculty.