# ICSE Class 9 Revision Notes

Class 9th is considered an important stage in academic life, and it lays down the foundation for class 10th boards. When a student is promoted to class 9, all concepts are upgraded, and some students may find it more difficult. Students must focus on their studies from the start of the session to perform well in the class 9th exam. They can prepare a fixed study schedule and access ICSE Class 9 Revision Notes to prepare well for their exams. Students must maintain subject-specific notes to make it easier to understand the concepts.

## ICSE Class 9 Revision Notes and Short Key Notes

The revision for ICSE notes 9 is important for students because it helps them understand concepts more clearly. There are several subjects in class 9 that are equally important, and thus, students have to learn plenty of concepts throughout the year. After completing each subject, students should begin preparing short keynotes, which will help them understand concepts properly. Students can visit the Extramarks website and access ICSE class 9 notes. These notes are compiled by experts and will definitely help students score well in the exam.

### Revision Notes for ICSE Class 9

Students in class 9 can refer to the ICSE Class 9 notes given below:

#### Mathematics

Number System

The number system is a writing system to express numbers. It is a collection of various symbols known as digits. Types of number systems are given below:

• Decimal number system [Base – 10]
• Octal number system [Base – 8]
• Binary number system [Base – 2]
• Hexadecimal number system [Base – 16]

Polynomial

A polynomial is an algebraic expression in which exponents of all variables should be a whole number.

• A function is represented by a polynomial
• The term polynomial is taken from a Greek word which means multiple terms
• The expression of a polynomial is made by the combination of constants and variables

Various types of polynomials are mentioned below:

• Trinomials
• Binomials
• Monomials

Triangles

• A triangle is defined as a plane figure with three angles and sides
• The whole sum of a triangle is equal to 180 degrees
• The sum of the exterior angles is equal to 360 degrees

The different types of triangles classified according to their sides and angles are as follows:

• Obtuse-angled Triangle
• Right-angled Triangle
• Acute-angled Triangle
• Scalene Triangle
• Isosceles Triangle
• Equilateral Triangle
• A quadrilateral is defined as a polygon with four vertices and sides
• The sum of interior angles of a quadrilateral is equal to 360 degrees

Special types of quadrilaterals are as follows:

• Parallelograms
• Trapezium
• Rectangle
• Rhombus
• Square

Different properties of a quadrilateral are mentioned below:

• A quadrilateral with opposite sides equal and all the four angles at 90 degrees is known as a rectangle
• A quadrilateral with equal sides and angles is known as a square
• The sum of interior angles of a quadrilateral is 360 degrees
• Each quadrilateral has four vertices and sides containing four angles

#### Science

1. The three main states of matter are solid, liquid and gas.

Students will be able to understand the following concepts:

• Physical nature of matter
• Characteristics of the particle of matter
• States of matter
• Particles that can generate matter
1. The sound chapter will help students in learning various important topics given below:
• Propagation of sound
1. Speed of sound in different media
2. Characteristics of a sound wave
3. Sound waves are longitudinal waves
4. Sound needs a medium to travel
• Production of sound
• Structure of the human ear
• Applications of ultrasound
1. Sonar
• Range of hearing
• Reflection of sound
• Uses of multiple reflections of sound
• Reverberation
• Echo
1. Tissues are groups of cells that have similar structures and perform different functions in the body as a unit.various forms of tissues are mentioned below:
• Nervous tissue
• Muscle tissue
• Connective tissue
• Epithelial tissue
1. A cell is known as the structural and functional unit of life. The main constituents of the cell are:
• Cell membrane
• Nucleus
• Cytoplasm

The main functions of the cell are as follows:

• They help in reproduction
• They create metabolic reactions
• They generate energy to carry out daily tasks
• They support processes like active and passive transport
• They provide the necessary structure and support

#### Social Sciences

• Food security is defined as the ability of people to afford and secure a sufficient amount of food for themselves and their families.
• In 1983, the Food and Agricultural Organisation defined food security as a process in which people have physical and economic access to the basic food items they need.

Different aspects of food security are mentioned below:

• Availability of food: The country should implement policies that can meet every citizen’s food needs.
• Affordability of food: Every citizen of the country must have sufficient money to buy food for themselves and their families

The following criteria are used to classify economies:

• On the basis of the level of development
• On the basis of ownership over the means of production
• On the basis of nature

The Economy is also classified based on nature, as shown below:

• Agricultural or industrial economy
• Planned or unplanned economy
• Closed or open economy
• Simple or complex economy

A political party is defined as an organization or a group of like-minded people who share similar views on the country’s political issues.

The basic characteristics of political parties are as follows:

• Unity
• An organised system of working
• Constitutional means
• Objectives
• National interest

The objectives of the political party are mentioned below:

• To provide a proper platform for people who are divided by cultural, social, and religious factors to come together
• To provide public leaders who can contribute to the country’s development
• To take power and form a government

Elections are a process by which people can elect their own representatives to run a practical government. There are two types of primary elections:

• Mid-term elections
• General elections

The chapter also discusses Indirect and Direct elections.

#### English

• Henry Cuyler is the author of the poem ‘Heart of the Tree’
• He successfully paints a picture of trees and the gifts they provide to human beings
• Through this poem, the poet raises questions about humanity and difficult issues that people face in their lives
• The Chief Seattle Speech provides information on both time and space
• The speech was originally written in the form of a letter
• The speech has been adapted and translated into different languages
• Chief Seattle was a tribal chief of Red Indian Tribes

### Benefits of Revision Notes for Class 9 Students

Taking notes may seem boring or difficult to some students, but it is extremely helpful during exam preparation. The majority of students wait until the last minute to prepare their revision notes because they are quite useful in exam preparation. Making revision notes for class 9 has several benefits, which are listed below-

• They help students understand the syllabus
• Students learn what they’ll study in the chapter
• The revision notes help students learn all the concepts in any subject easily
• Writing down revision notes help students memorize concepts
• When students are unable to memorize long answers, revision notes come in handy for the last-minute preparation
• Revision notes consist of important definitions, terms, and concepts that assist students in finishing the syllabus on time

## Revision Notes for ICSE Class 9

### 1. Are revision notes necessary for class 9?

Yes, revision notes for class 9 are necessary because they help students in their exam preparation.

### 2. How should I prepare my class 9 revision notes?

Students can make revision notes by writing down key concepts from the chapter or subject, such as definitions, formulas, diagrams, brief answers, etc.

### 3. Will ICSE revision notes help me in the exam?

Yes, ICSE revision notes for class 9 will help students in exam preparation at the last minute. Long answers may be difficult for students to memorise, so revision notes may be useful for last-minute preparation.