NCERT Solutions: Chapter1 Exploring the Investigative World of Science (class 8 Science)

Curiosity begins with observing everyday phenomena and asking 'why' and 'how'. Examples of questions that spark scientific inquiry include:[cite: 8]

• Why does rice cook faster in a pressure cooker than in an open vessel?[cite: 8]
• Why do cut apples turn brown after some time?[cite: 8]
• Why does ice melt faster in warm water than in cold water?[cite: 8]

(Note: Questions may vary as individual observations and curiosity differ from person to person.)[cite: 8]

Nature has created a vast variety of plants and animals to maintain balance in ecosystems.[cite: 8] Each organism plays a distinct ecological role—such as producing food, pollinating plants, recycling nutrients, or regulating populations—ensuring the stability and continuity of life.[cite: 8]

• A root at the bottom of the left pages represents deep knowledge (firmly grounded understanding).[cite: 8]
• A kite on top of the right pages represents curiosity and imagination (soaring to explore new ideas).[cite: 8]

To investigate like a scientist means:[cite: 8]

• Asking specific, testable questions.[cite: 8]
• Designing controlled experiments.[cite: 8]
• Making precise, unbiased observations.[cite: 8]
• Measuring data accurately.[cite: 8]
• Drawing logical conclusions one step at a time based on evidence.[cite: 8]

Curiosity is the starting point of Science.[cite: 8] Asking "why" and "how" helps us initiate scientific inquiries, challenge assumptions, and discover new knowledge about how nature works.[cite: 8]

The following key themes and chapters will be covered this year:[cite: 8]

• Microbes and health[cite: 8]
• Electricity and its effects[cite: 8]
• Force, pressure, and motion[cite: 8]
• Particles, elements, compounds, mixtures[cite: 8]
• Light: reflection, mirrors, and lenses[cite: 8]
• Phases of the Moon and calendars[cite: 8]
• Ecosystems and climate change[cite: 8]

Human actions like burning fossil fuels (releasing excessive greenhouse gases) and large-scale deforestation can change the Earth's global temperature, disrupt natural climate and weather patterns, and cause serious ecological and environmental consequences.[cite: 8]

When a rolled dough puri is immersed in hot oil, moisture converts into steam inside it.[cite: 8] The expanding steam pushes outward, inflating the puri and stretching the upper layer more, making that side thinner.[cite: 8] This difference also depends on initial dough thickness, oil temperature, and the orientation in which the puri is placed into the hot oil.[cite: 8]

Puris usually puff better when made from fresh dough rather than stored dough.[cite: 8]

• Fresh Dough: Has optimal moisture content, elasticity, and softness, which allows the steam formed inside to expand evenly and puff the puri completely.[cite: 8]
• Stored Dough: Often loses moisture, developing a dry and hard outer crust that resists steam expansion, making it difficult for the puri to puff properly.[cite: 8]

A systematic investigation is a methodical experimental approach in which:[cite: 8]

• Only one variable is changed (tested) at a time.[cite: 8]
• All other factors and conditions are kept strictly constant (controlled variables).[cite: 8]
• Careful, step-by-step observations, measurements, and recorded data are compiled to establish a valid conclusion.[cite: 8]