IJSO Syllabus 2026: Subject-Wise Topics & PDF

The International Junior Science Olympiad (IJSO) is a general science competition that tests students on concepts from natural sciences and mathematics. The syllabus focuses on scientific understanding rather than dividing the subjects strictly into physics, chemistry, and biology.

The IJSO 2026 Syllabus covers general science skills, natural sciences and mathematics, laboratory skills, and interdisciplinary concepts. It also encourages students to understand how different scientific areas are connected.

The syllabus was accepted at the 6th IJSO in Baku, Azerbaijan, in 2009 and was revised by the International Board in December 2020. It is designed to guide students and participating countries in preparing for the competition.

IJSO Subject-Wise Syllabus

The IJSO subject-wise syllabus can be understood through the major sections given below. The syllabus includes general science, chemistry, physics, biology, mathematics, and practical laboratory skills.

General Science Skills

You should be familiar with the following scientific skills:

• Scientific methods and their application

• Use of scientific terminology

• Forming hypotheses and making predictions

• Planning experiments and identifying suitable controls

• Drawing conclusions from experiments

• Representing data through tables, diagrams, and graphs

• Interpreting and validating experimental data

• Understanding precision and accuracy

• SI units and derived units

• Dimensional analysis

• Measurement of length, mass, time, temperature, volume, density, pressure, displacement, speed, velocity, acceleration, force, potential difference, current, resistance, electrical power, energy, and amount of substance

• Significant figures

• Identification of sources of error

• Scientific notation and rounding

IJSO Syllabus for Natural Sciences

The natural science section forms a major part of the IJSO Syllabus. Instead of keeping physics, chemistry, and biology completely separate, the syllabus focuses on broader scientific concepts.

1. Particles, Waves and Matter

The topics related to matter and its properties include:

• Conservation of mass

• States of matter and their properties

• Gases, liquids, solids, and plasmas

• Volume, shape, and particle movement in different states

• Effect of temperature and pressure on states of matter

• Phase transitions and latent heat

• Water and its different phases

• Phase diagrams of water

• Elements, compounds, and mixtures

• Atomic theory

• Electrons, protons, and neutrons

• Atomic number and mass number

• Isotopes and atomic mass

• Atomic mass unit

• Molecular mass and formula mass

• Avogadro's constant

• Molar mass

• Electron shells

• Electron configurations of simple atoms and ions of the first 20 elements

• Modern basis of the Periodic Table

• Periodic trends such as ionisation energy, boiling point, melting point, hardness, electronegativity, and electron affinity

• Metallic nature of non-transition elements

• Metals, metalloids, and non-metals

• Oxides and their acid-base nature

• Chemical formulas of molecular and ionic substances

• Acids and corresponding anions

• Binary molecular and ionic compounds

• Empirical and molecular formulas

2. Chemistry

Chemistry topics in the IJSO exam syllabus include calculations, chemical reactions, bonding, reaction rates, equilibrium, gases, energy, and electrochemistry.

Chemical Calculations

• Mole concept

• Conversion between mass and moles

• Mass percentages

• Yield of chemical reactions

• Molar concentration

• Dilution of solutions

Chemical Reactions

• Balancing chemical equations

• Solubility of ionic compounds

• Precipitation reactions

• Acid-base reactions

• Oxidation numbers

• Oxidation-reduction reactions

• Combination, decomposition, displacement, and combustion reactions

• Half-reaction method for balancing redox reactions

• Net ionic equations

Chemical Bonding

• Ionic bonds

• Covalent bonds

• Metallic bonds

• Polar covalent bonds

• Properties of ionic and covalent compounds

• Properties of metals and covalent lattices

• Intermolecular forces

• van der Waals forces

• Hydrogen bonding

• Relationship between intermolecular forces and physical properties

Reaction Rates and Equilibrium

• Definition of reaction rate

• Instantaneous and average rates

• Rate expressions

• Factors affecting reaction rates

• Determination of the rate constant for first-order reactions

• Equilibrium conditions

• Equilibrium constants

• Homogeneous and heterogeneous equilibria

• Equilibrium concentrations

• Effect of reactants, products, and temperature on equilibrium

• Effect of catalysts on equilibrium

Acids and Bases

• Acids and bases

• Strong and weak acids and bases

• Arrhenius concept

• Brønsted-Lowry concept

• Lewis concept

• Conjugate acid-base pairs

• Self-ionisation of water

• pH

• Strong acid and strong base calculations

• pH scale and indicators

• Degree of ionisation

• Ka and Kb

• Acid-base titration curves

• Choice of indicators

• Common ion effect

• Buffer solutions

• Solubility product and solubility

Gaseous State

• Boyle's law

• Charles's law

• Combined gas law

• Avogadro's law

• Ideal gas law

• Partial pressure

• Mole fraction

• Diffusion and effusion

Energy in Chemistry

• Exothermic and endothermic reactions

• Enthalpy of reactions

• Combustion

• Formation

• Hydration

• Phase changes

• Hess's law

• Simple calculations using enthalpy diagrams

Electricity and Chemistry

• Structure of electrochemical cells

• Electrodes and electrolytes

• Salt bridges

• Anodes and cathodes

• Direction of current in electrochemical cells

• Standard electrode potentials

• Half-cell reactions

• Full cell reactions

• Electron transfer

• Electrolysis of molten sodium chloride

3. Physics

The physics portion covers energy, waves, optics, sound, electricity, magnetism, heat, fluids, and elementary nuclear science.

Energy, Work and Power

• Conservation of energy

• Energy conversion and transformation

• Sources and nature of energy

• Mechanical energy

• Potential and kinetic energy

• Thermal energy

• Electromagnetic energy

• Chemical energy

• Nuclear energy

• Energy transfer

• Heat transfer

• Energy transfer through waves

• Work done by a constant force

• Work-energy theorem

• Mass-energy relation

• Power

• Efficiency

• Effects of energy use on life and the environment

• Fossil fuels

• Renewable and non-renewable resources

Oscillations and Waves

• Harmonic oscillations

• Frequency

• Period

• General properties of waves

• Reflection and refraction

• Diffraction

• Interference

• Superposition

• Transverse and longitudinal waves

• Relationship between wave velocity, frequency, and wavelength

Light and Optics

• Characteristics of light

• Propagation of light

• Formation of shadows

• Linear spreading of light

• Reflection

• Refraction

• Spherical lenses

• Spherical and plane mirrors

• Electromagnetic spectrum

• Visible spectrum

• Colours and wavelengths

• Dispersion

• Photoelectric effect

Sound

• Characteristics of sound

• Sound as a wave

• Microphones and speakers

• Sound as a longitudinal pressure wave

• Perception of sound

• Classical Doppler effect

Electricity and Magnetism

• Electrical characteristics of materials

• Static electricity

• Coulomb's law

• Dynamic electricity

• Ohm's law

• Electric interaction

• Electric current

• Electric circuits

• Electric energy

• Electrical work

• Electric power

• Electric sources

• Electric potential

• Electromotive force

• Electric fields

• Motion of charged particles

• Series and parallel circuits

• Kirchhoff's laws

• Resistance and conductance

• Dielectrics

• Semiconductor diodes

• Magnets and magnetic materials

• Magnetic fields and poles

• AC and DC

• Electromagnetic induction

• Lenz's law

• Safe use of electricity

• Generators, transformers, and motors

Heat and Mass Transfer

• Thermodynamic systems

• Properties and temperature

• Thermal conduction

• Convection

• Radiation

• Evaporation

• Insulation

• Specific heat capacity

• Calorimetry

• Changes in state

• Latent heat

• First law of thermodynamics

• Pascal's law

• Kinetic molecular model of matter

• Basic Bernoulli principle

Elementary Nuclear Science

• Isotopes

• Radioactivity

• Half-life

Earth, Astronomy and Space

• Solar system

• Sun, Moon, and planets

• Kepler's laws

• Structure of the universe

IJSO Biology Syllabus

Biology covers living organisms from the molecular and cellular levels to human biology and ecosystems. The IJSO Syllabus also includes genetics, evolution, plant biology, animal biology, and preventive biology.

Biochemistry

• Chemical composition of living organisms

• Organic and inorganic components

• Carbohydrates and their monomers

• Proteins and their monomers

• Nucleic acids and their monomers

• Lipids

• Nutrition and nutrients

• Macronutrients

• Micronutrients

Diversity and Structure of Life

• Characteristics of living organisms

• Taxonomy and classification

• Phylogenetic trees

• Cladistics

• Organisation from cells to organisms

• Monera

• Protists

• Plants

• Fungi

• Animals

• Microorganisms and pathogens

• Viruses

• Asexual reproduction

• Sexual reproduction

Cell Biology

• Cell as a system

• Cell wall

• Cell membrane

• Vacuole

• Cytoplasm

• Nucleus

• Ribosomes

• Chloroplasts

• Mitochondria

• Plant, animal, and bacterial cells

• Diffusion

• Osmosis

• Active transport

• Aerobic respiration

• Anaerobic respiration

• Fermentation

• Haploidy and diploidy

• Gametogenesis

• Cell cycle

• Cell division

• Mitosis

• Meiosis

Genetics and Evolution

• Chromosomal basis of inheritance

• Variation of traits

• Genes as parts of chromosomes

• DNA replication

• Mendelian genetics

• Alleles

• Dominant and recessive traits

• Homozygotes and heterozygotes

• Mendel's first and second laws

• Family pedigrees

• Sex-linked inheritance

• Monohybrid crosses

• Mutations

• Genetic defects

• Theory of evolution

• Natural selection

Plant Structure and Function

• Primary plant tissues

• Assimilation, covering, support, and circulation tissues

• Plant nutrition

• Soil and mineral nutrients

• Absorption by roots

• Transpiration

• Photosynthesis

• C3 pathway

• C4 and CAM pathways

• Factors affecting respiration and photosynthesis

• Phytohormones

• Auxins

• Gibberellins

• Ethylene

• Abscisic acid

• Tropism and plant movements

• Pollination

• Seed dispersal

• Sexual reproduction in angiosperms

• Vegetative reproduction

Animal Structure and Function

• Animal tissues

• Epithelial tissue

• Connective tissue

• Blood and bones

• Muscular tissue

• Nervous tissue

• Support systems

• Animal nutrition

• Alimentary systems of carnivores, herbivores, and omnivores

• Sense organs

• Communication cues and signals

• Animal orientation

• Reproductive patterns

• Fertilisation

• Hormones in sexual development

• Gamete maturation

• Metamorphosis

• Relationship between human anatomy and physiology

Human Biology

• Integumentary system

• Skeletal system

• Muscles

• Blood and circulatory system

• Digestive system

• Respiratory system

• Excretory system

• Endocrine system

• Nervous system

• Sensory organs

• Reproductive system

• Human fertilisation

• Human reproductive organs

• Sex cells

• Changes during puberty

Preventive Biology

• Effects of tobacco, alcohol, and opioid-like drugs on the human body

• Genetic, lifestyle, and environmental factors affecting long-term health

• Immune system

• Vaccination

• Microorganisms causing common and infectious diseases

• HIV and AIDS

IJSO Topics for Ecology and Environment

The ecology section focuses on relationships between organisms and their environment. The important areas include:

• Role of organisms in matter and energy circulation

• Water cycle

• Carbon cycle

• Oxygen cycle

• Nitrogen cycle

• Producers, consumers, and decomposers

• Food chains

• Food webs

• Abiotic and biotic factors

• Terrestrial ecosystems

• Aquatic ecosystems

• Environmental adaptation

• Structural, physiological, and behavioural adaptations

• Competition

• Predation

• Symbiosis

• Population growth

• Population growth curves

• Reproductive behaviour in animals

• Courtship and mating

• Parental care

• Ecological balance

• Ecological succession

• Pollution

• Acid rain

• Global warming

• Carbon footprint

• Human activities and their effects on ecosystems

• Biodiversity

• Sustainable development

Mathematics Skills in IJSO

Mathematics is used as a tool for solving science-based problems. The mathematics portion includes:

• Equations involving fractions

• Logarithms

• Powers and roots

• Polynomials

• Quadratic equations

• Trigonometric functions

• Plotting named functions

• Transforming equations into linear relations

• Basic geometry

• Fundamentals of stereometry

• Triangles and circles

• Areas of basic plane figures

• Volumes of basic solid figures

• Surface areas of basic solid figures

• Basic vector algebra

• Vector decomposition and addition

• Mean values

• Qualitative understanding of measurement uncertainty

Laboratory Skills in IJSO

Practical knowledge is also part of the IJSO syllabus. You should be familiar with laboratory work and follow appropriate safety practices.

• Laboratory safety regulations

• Measurement of mass, length, volume, time, and temperature

• Measurement of voltage and current

• Use of dichotomous keys

• Dissection of plant specimens such as roots, stems, leaves, fruits, and flowers

• Light microscopy

• Preparation of slides

• Preparation of standard solutions

• Titrations

• Spectrophotometry

• Beer-Lambert's law when the formula is provided

• Filtration

• Simple distillation

• Crystallisation

• Thin-layer chromatography

• Adsorption

• Centrifugation

• Measurement of pH

• Measurement of focal length of a thin lens

IJSO Syllabus PDF

You can download the official IJSO Syllabus PDF to check the complete list of topics, scientific skills, mathematics concepts, and laboratory skills included in the syllabus. Keep the PDF as a reference while planning your preparation and revising different sections.

Download IJSO Syllabus PDF

The IJSO syllabus is designed around scientific concepts and their application. Therefore, while preparing, you should focus on understanding how concepts work and how they can be applied to experimental and problem-solving situations.

Related Resources:

• IJSO Exam Date 2026

• PW Olympiad Online Batches

• PW Olympiad Test Series