Science · Class 7

A child in Class 6, 7 or 8 can read this book alone, understand every topic in the year's syllabus, and answer the school's own tests on it — no tutor, no parent sitting beside them.

That means the explaining is done here, on the page. It follows the NCERT textbook the school uses, chapter by chapter. Each chapter starts at the beginning, explains the idea in plain words, works an example before it asks a question. Every question is worked out at the back, so a wrong answer can be checked the same evening.

Science, Class 7, on the 2026–27 NCERT course.

1. The Ever-Evolving World

   • Science as a process of inquiry, not a collection of facts
   • Invitation to question, experiment, and explore
   • Overview of topics covered across the book (orientation chapter — no testable content)
2. Acids, Bases and Neutrals

   • Acids, bases, and neutral substances — classification by behaviour with indicators
   • Litmus as an acid-base indicator (blue litmus turns red in acid; red litmus turns blue in base)
   • Natural indicators: red rose extract, turmeric paper, purple cabbage, beetroot, red hibiscus
   • Olfactory indicators (onion strips lose smell in base)
   • Acids taste sour; bases feel soapy and taste bitter
   • Neutralisation reaction: acid + base → salt + water + heat
   • Applications of neutralisation: ant-bite relief (formic acid + baking soda), soil treatment (lime for acidic soil; organic matter for basic soil), industrial effluent treatment
   • Soil pH and plant health; over-use of fertilisers causing soil acidity
3. Electric Circuits

   • Electric cell as a portable source of electrical energy; positive and negative terminals
   • Battery: two or more cells connected in series (positive terminal of one to negative of next)
   • Incandescent lamp: filament glows when current passes through it; fused lamp = broken filament
   • LED (Light Emitting Diode): no filament; current flows in one direction only; polarity matters
   • Electrical circuit: complete path for current to flow; current direction = positive to negative terminal
   • Open circuit vs closed circuit; role of a switch (completes or breaks the circuit)
   • Circuit diagrams: standardised symbols for cell, battery, lamp, LED, switch, wire
   • Conductors of electricity: metals (silver, copper, gold best; copper used for wires)
   • Insulators: rubber, plastic, ceramics; used to cover wires and protect from shock
   • DC (from cells/batteries) vs AC (from wall sockets) — introduced briefly
4. The World of Metals

   • Properties of metals: lustre, malleability (beaten into sheets), ductility (drawn into wires), sonority (rings when struck), heat conduction, electrical conduction
   • Properties of non-metals: generally non-lustrous, not malleable or ductile, poor conductors of heat and electricity
   • Metals react with oxygen → metal oxides (basic in nature)
   • Non-metals react with oxygen → non-metal oxides (acidic in nature)
   • Corrosion: metal objects damaged by exposure to moist air (iron rusts, copper turns green)
   • Substances with mixed properties (e.g., graphite — non-metal but conducts electricity; iodine — non-metal with lustre)
   • Everyday applications of metals and non-metals
5. Physical & Chemical Changes

   • Physical change: change in size, shape, or state; no new substance formed; generally reversible (ice melting, cutting paper, chopping vegetables)
   • Chemical change: new substance(s) formed; involves a chemical reaction; generally irreversible (burning wood, rusting, cooking, ripening fruit)
   • Chemical equation as a representation of chemical change
   • Combustion: burning of a substance with heat and/or light; combustible vs non-combustible substances; ignition temperature
   • Rusting: iron + moisture + oxygen → rust (iron oxide); a chemical change
   • Reversible vs irreversible changes
   • Desirable vs undesirable changes
   • Weathering of rocks: physical (wind, water erosion) and chemical changes producing soil
   • Erosion by flowing water and wind = physical change
6. Adolescence

   • Adolescence: period from childhood to adulthood, approximately ages 10–19
   • Puberty: observable and internal body changes enabling reproduction
   • Physical changes in boys and girls (height spurt, voice change, body hair, skin changes)
   • Secondary sexual characteristics: features distinguishing male and female not directly involved in reproduction
   • Menstrual cycle: discharge of blood approximately every 28–30 days; begins at puberty, ends at 45–55 years (menopause)
   • Emotional and behavioural changes during adolescence
   • Hormones: chemicals produced in the body controlling adolescent changes
   • Nutritional needs of adolescents: balanced diet, importance of iron and calcium
   • Personal hygiene during adolescence
   • Physical activity and balanced social life
   • Harmful substances: tobacco, alcohol, drugs — adverse effects; developing refusal skills
7. Heat Transfer

   • Three modes of heat transfer: conduction, convection, radiation
   • Conduction: heat transfer from hotter to cooler part; particles do not move (mainly in solids); conductors and insulators of heat
   • Convection: heat transfer by actual movement of particles (liquids and gases); land and sea breezes as examples
   • Radiation: heat transfer without medium; Sun's heat reaches Earth by radiation; all objects exchange heat with surroundings via radiation
   • Conduction and convection require a medium; radiation does not
   • Application in house design and clothing (insulation principles)
   • Water cycle: evaporation → condensation → precipitation → infiltration → groundwater → return to water bodies
   • Infiltration: surface water seeping through soil and rocks
   • Groundwater and its role; connection to springs and wells
8. Time and Motion

   • Measurement of time: historical devices — sundials, water clocks, hourglasses, candle clocks
   • Simple pendulum: bob, string, mean position, oscillation, time period
   • Time period of a pendulum: constant for a given length at a given place; independent of amplitude (for small swings)
   • SI unit of time: second (s)
   • Speed = total distance ÷ total time taken
   • SI unit of speed: m/s; also expressed in km/h
   • Uniform linear motion: constant speed along a straight line
   • Non-uniform linear motion: changing speed along a straight line
   • Distance–time graphs: straight line = uniform motion; curved line = non-uniform motion
9. Life Processes in Animals

   • Life processes: nutrition, respiration, circulation, excretion, reproduction — essential for survival
   • Nutrition in humans: digestion in the alimentary canal (mouth → oesophagus → stomach → small intestine → large intestine → anus); associated glands: liver and pancreas
   • Digestion: mechanical (chewing) and chemical breakdown of food; absorption primarily in small intestine
   • Large intestine: absorbs remaining water and salts from undigested matter
   • Ruminants (cows, goats): partial chewing → swallow → regurgitate → rechew (rumination)
   • Respiration in humans: inhalation/exhalation; gas exchange in alveoli of lungs (O₂ in, CO₂ out)
   • Cellular respiration: glucose + oxygen → carbon dioxide + water + energy
   • Breathing = physical process; respiration = chemical process (important distinction)
   • Circulatory system: heart pumps blood through blood vessels; delivers oxygen and nutrients, removes waste
   • Varied breathing mechanisms in other animals (gills in fish, skin in earthworms, spiracles in insects)
10. Life Processes in Plants

    • Plants grow using water, minerals from soil, and food synthesised in leaves
    • Leaves as "food factories": broad flat surface maximises sunlight capture
    • Photosynthesis: carbon dioxide + water → glucose + oxygen (sunlight + chlorophyll required)
    • Word equation for photosynthesis; glucose stored as starch
    • Stomata: tiny pores on leaf surface for gas exchange (CO₂ in, O₂ out during photosynthesis)
    • Chlorophyll: green pigment in leaves that captures sunlight
    • Xylem: transports water and minerals from roots to leaves
    • Phloem: transports food (glucose/sucrose) from leaves to all parts of the plant
    • Plant respiration: glucose + oxygen → carbon dioxide + water + energy (same as animals); occurs day and night
11. Light and Shadows

    • Sources of light: luminous objects (emit own light — Sun, stars, fire, fireflies) vs non-luminous objects (Moon, walls)
    • Light travels in a straight line (rectilinear propagation)
    • Transparent materials: light passes almost completely through (glass, clear water)
    • Translucent materials: light passes partially through (oiled paper, frosted glass)
    • Opaque materials: light does not pass through (wood, metal); form dark shadows
    • Shadow formation: requires a source of light, an opaque object, and a screen
    • Reflection of light: change in direction of light by a mirror
    • Plane mirror image: same size as object, erect, virtual (cannot be obtained on a screen), laterally inverted
    • Pinhole camera: creates an inverted image; demonstrates rectilinear propagation
    • Applications: periscope (two plane mirrors at 45°), kaleidoscope (multiple reflections creating patterns)
12. Earth, Moon and the Sun

    • Earth's rotation: on its own axis; approximately 24 hours; direction West to East
    • Rotation causes: day and night; apparent motion of Sun, Moon, and stars from East to West
    • Earth's revolution: around the Sun; approximately 365.25 days (1 year)
    • Earth's axis is tilted (not perpendicular to orbital plane)
    • Seasons: caused by tilt of Earth's axis plus its spherical shape; different hemispheres receive sunlight at different angles throughout the year
    • Changing night sky: constellations visible change with Earth's position in its orbit
    • Solar eclipse: Moon comes between Sun and Earth; blocks sunlight from reaching Earth; total and partial solar eclipses
    • Lunar eclipse: Earth comes between Sun and Moon; Earth's shadow falls on Moon
    • Caution regarding direct viewing of solar eclipse

It follows the NCERT Science textbook for Class 7 chapter by chapter, for 2026–27 — at this stage that textbook is the syllabus, since CBSE publishes none for Classes 6 to 8. Each chapter starts at the beginning, explains the idea in plain words, works an example before it asks a question, names the mistakes children actually make. Every question is worked out at the back, and the back matter carries a glossary of every term the book uses.

What it is not: an NCERT solutions book — it solves its own questions only; a question bank or sample-paper book; a coaching module or test series; a CBSE or NCERT publication; the school — no lab work, projects or internal-assessment help. It is not a workbook either — there is no space to write in it — and nothing in it needs a lab, an apparatus set, or anything you have to buy.