CLASS 7TH | UNIT 4: GEOMETRY | SYMMETRY (INCLUDING REFLECTION AND ROTATION) | REVISION NOTES

Line of Symmetry

  • When a shape coincides with another shape completely then they are said to have symmetry.
  • Symmetry can also be observed within a shape. When one part of a shape coincides with another part then they are said to have symmetry within a shape.
  •  The line which divides a shape into two identical parts is called a line of symmetry.
  • For Example: In the figure below the dotted line is the line of symmetry and left and right part looks identical or symmetrical.

(Image will be Uploaded Soon)

Lines of Symmetry for Regular polygon

  • Regular polygons are those polygons whose length of all sides and measure of angles are equal. 
  • In regular polygons lines of symmetry are equal to the sides of regular polygons.
  • For Example: 
  1. Triangle has three sides and three lines of symmetry.
  2. Square has four sides and four lines of symmetry.
  3. Regular pentagon has five sides and five lines of symmetry.
  4. Regular hexagon has six sides and six lines of symmetry.

Rotational Symmetry

  • When a shape is rotated at some angle about its axis clockwise or anticlockwise and after rotation if the shape looks exactly the same as it was before then it is called rotational symmetry.
  • The fixed point through which the shape is rotated is called centre of rotation.
  • The angle at which rotational symmetry occurs is called angle of rotation.
  • The number of times a shape looks the same on rotation is called order of rotational symmetry. 

For Example: Order of rotational symmetry of square is 4

Line Symmetry and Rotational Symmetry

  • There are some shapes which have line as well as rotational symmetry.
  • Circle is the perfect example of this type; it has infinite line symmetry and can be rotated around its centre through any angle i.e., it has rotational symmetry at any angle.
  • There are some alphabets also which show both line and rotational symmetry such as H, O, I and X.
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CLASS 7TH | UNIT 1: NUMBER SYSTEM | EXPONENTS (INCLUDING LAWS OF EXPONENTS) | REVISION NOTES

1. Exponents:

Exponents are used to convey huge numbers in a more readable, understandable, comparable, and manipulable format.

2. Expressing Large Numbers in the Standard Form:

  • Any number between 1.01.0 and 10.010.0 (including 1.01.0) multiplied by a power of ten can be expressed as a decimal number between 1.01.0 and 10.010.0(including 1.01.0).
  • The standard form of a number is also known as scientific motion.

3. Large numbers are difficult to read, comprehend, compare, and manipulate. 

4. We use exponents to make all of this easier by transforming many of the enormous numbers into a shorter form.

5. What are some examples of exponential forms of numbers?

100=102100=102 (It can be read as 1010 raised to 22)

512=83512=83

243=35243=35

Here, 10, 810, 8 and 33 are the bases, whereas 2, 32, 3 and 55 are their respective exponents.

We also can say that

100100 is the 2nd2nd power of 1010 , 

512512 is the 3rd3rd power of 88 , 

243243 is the 5th5th power of 33 , etc.

6. For any non-zero integers aa and bb, and whole numbers mm and nn, numbers in exponential form obey the following laws:

a. am × an = am+nam × an = am+n

b. am ÷ an = am-n , m  nam ÷ an = am-n , m  n

c. (am)n = amn(am)n = amn

d. am × bm = (ab)mam × bm = (ab)m

e. am ÷ bm = (ab)mam ÷ bm = (ab)m

f. a0 = 1a0 = 1

g. (-1)(even number) = 1

h. (-1)(odd number) = -1Is this page helpful?Related QuestionsIf xa=yxa=y,yb=zyb=zand zc=xzc=x, then prove that abc=1abc=1

Prove that the following equation is correct 3−3×62×98−−√52×125−−−√3×(15)−43×313=282–√

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CLASS 7TH | UNIT 1: NUMBER SYSTEM | DECIMAL FRACTIONS (DECIMALS) | REVISION NOTES

Decimals

Introduction: Decimal

Decimal numbers are used to represent numbers that are smaller than the unit 1. Decimal number system is also known as base 10 system since each place value is denoted by a power of 10.

Decimals

A decimal number refers to a number consisting of the following two parts:
(i) Integral part (before the decimal point)
(ii) Fractional Part (after the decimal point).
These both are separated by a decimal separator(.) called the decimal point.

A decimal number is written as follows: Example 564.8 or 23.97.
The numbers to the left of the decimal point increase with the order of 10, while the numbers to the right of the point increase with the decrease order of 10.
The above example 564.8 can be read as ‘five hundred and sixty four and eight tenths’
⇒5×100 + 6×10 + 4×1 + 8×(1/10)

fraction can be written as a decimal and vice-versa. Example 3/2 = 1.5 or 1.5 = 15/10 = 3/2

Multiplication of Decimals

Multiplication of decimal numbers with whole numbers :
Multiply them as whole numbers. The product will contain the same number of digits after the decimal point as that of the decimal number.
E.g : 11.3×4 = 45.2

Multiplication of decimals with powers of 10 :
If a decimal is multiplied by a power of 10, then the decimal point shifts to the right by the number of zeros in its power.
E.g : 45.678×10 = 456.78 (decimal point shifts by 1 place to the right) or, 45.678×1000 = 45678 (decimal point shifts by 3 places to the right)

Multiplication of decimals with decimals :

Multiply the decimal numbers without decimal points and then give decimal point in the answer as many places same as the total number of places right to the decimal points in both numbers.

E.g :

Multiplication of decimals with decimals

Division of Decimals

Dividing a decimal number by a whole number:
Example: 45.2/55
Step 1. Convert the Decimal number into Fraction: 45.25= 4525/100
Step 2. Divide the fraction by the whole number: (4525/100)÷5 = (4525/100) × (1/5) = 9.05

Dividing decimal number by a decimal number:
Example 1: 45.25/0.5
Step 1. Convert both the decimal numbers into fractions: 45.25 = 4525/100 and 0.5 = 5/10
Step 2. Divide the fractions: (4525/100)÷(5/10) = (4525/100)×(10/5) = 90.5
Example 2:

Dividing a decimal number by a decimal number

Dividing decimal number by powers of 10  :
If a decimal is divided by a power of 10, then the decimal point shifts to the left by the number of zeros present in the power of 10.
Example: 98.765÷100=0.98765 Infinity

When the denominator in a fraction is very very small (almost tending to 0), then the value of the fraction tends towards infinity.
E.g: 999999/0.000001 = 999999000001 ≈ a very large number, which is considered to be ∞

1. How to multiply a decimal number with a whole number?

If we have to multiply the whole number with a decimal number then we will multiply them as normal numbers but the decimal place will remain the same as it was in the original decimal number.

Example

35 × 3.45 = 120.75

Here we have multiplied the number 35 with 345 as normal whole numbers and we put the decimal at the same place from the right as it was in 3.45.

2. How to multiply Decimal numbers by 10,100 and 1000?

a. If we have to multiply a decimal number by 10 then we will transfer the decimal point to the right by one place.

Example

5.37 × 10 = 53.7

b. If we have to multiply a decimal number by 100 then we will transfer the decimal point to the right by two places.

Example

5.37 × 100 = 537

c. If we have to multiply a decimal number by 1000 then we will transfer the decimal point to the right by three places.

Example

5.37 × 1000 = 5370

3. How to multiply a decimal number by another decimal number?

To multiply a decimal number with another decimal number we have to multiply them as the normal whole numbers then put the decimal at such place so that the number of decimal place in the product is equal to the sum of the decimal places in the given decimal numbers.

Example

Decimal number

Division of Decimal Numbers

1. How to divide a decimal number with a whole number?

If we have to divide the whole number with a decimal number then we will divide them as whole numbers but the decimal place will remain the same as it was in the original decimal number.

Example

12.96 ÷ 4 = 3.24

Here we divide the number 1296 with 4 as normal whole numbers and we put the decimal at the same place from the right as it was in 12.96.

2. How to divide Decimal numbers by 10,100 and 1000?

a. If we have to divide a decimal number by 10 then we will transfer the decimal point to the left by one place.

Example

5.37 ÷ 10 = 0.537

b. If we have to divide a decimal number by 100 then we will transfer the decimal point to the left by two places.

Example

253.37 × 100 = 2.5337

c. If we have to divide a decimal number by 1000 then we will transfer the decimal point to the left by three places.

Example

255.37 × 1000 = 0.25537

3. How to divide a decimal number by another decimal number?

To divide a decimal number with another decimal number

  • First, we have to convert the denominator as the whole number by multiplying both the numerator and denominator by 10, 100 etc
  • Now we can divide them as we had done before.

Example

Here we had converted denominator 2.4 in the whole number by multiplying by 10.Then divide it as usual

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CLASS 7TH | UNIT 1: NUMBER SYSTEM | FRACTIONS (INCLUDING PROBLEMS) | REVISION NOTES

Introduction: Fractions

The word fraction derives from the Latin word “Fractus” meaning broken. It represents a part of a whole, consisting of a number of equal parts out of a whole.
E.g : slices of a pizza.

Fractions

Representation of Fractions

fraction is represented by 2 numbers on top of each other, separated by a line. The number on top is the numerator and the number below is the denominator. Example :34  which basically means 3 parts out of 4 equal divisions.

Fractions on the Number Line

In order to represent a fraction on a number line, we divide the line segment between two whole numbers into n equal parts, where n is the denominator.
Example: To represent 1/5 or 3/5, we divide the line between 0 and 1 in 5 equal parts. Then the numerator gives the number of divisions to mark.

Fractions on the Number Line

Multiplication of Fractions

Multiplication of Fractions

Multiplication of a fraction by a whole number :
Example 1: 7×(1/3) = 7/3
Example 2 : 5×(7/45) = 35/45, Dividing numerator and denominator by 5, we get 7/9

Multiplication of a fraction by a fraction is basically product of numerators/product of denominators

Example 1: (3/5) × (12/13) = 36/65
Example 2 : Multiplication of mixed fractions

First convert mixed fractions to improper fractions and then multiply
143×87

Fraction as an Operator ‘Of’

The ‘of’ operator basically implies multiplication.

Example: 1/6 of 18 = (1/6)×18 = 18/6 = 3
or, 1/2 of 11 = (1/2) × 11 = 11/2 

Division of Fractions

Reciprocal of a Fraction

Reciprocal of any number n is written as1n
Reciprocal of a fraction is obtained by interchanging the numerator and denominator.
Example: Reciprocal of 2/5 is 5/2
Although zero divided by any number means zero itself, we cannot find reciprocals for them, as a number divided by 0 is undefined.
Example : Reciprocal of 0/7 ≠ 7/0

Division of Fractions

Division of a whole number by a fraction : we multiply the whole number with the reciprocal of the fraction.
Example: 63÷(7/5) = 63×(5/7) = 9×5 = 45

Division of a fraction by a whole number: we multiply the fraction with the reciprocal of the whole number.
Example: (8/11)÷4 = (8/11)×(1/4) = 2/11

Division of a fraction by another fraction : We multiply the dividend with the reciprocal of the divisor.
Example: (2/7) ÷ (5/21) = (2/7) × (21/5) = 6/5

Types of Fractions

Types of Fractions

Proper fractions represent a part of a whole. The numerator is smaller than the denominator.
Example: 1/4, 7/9, 50/51. Proper fractions are greater than 0 and less than 1

Improper fractions have a numerator that is greater than or equal to the denominator.
Example: 45/6, 6/5. Improper fractions are greater than 1 or equal to 1.

Mixed fractions are a combination of a whole number and a proper fraction.
Example: 43/5 can be written as .

Conversion of fractions : An improper fraction can be represented as mixed fraction and  a mixed fraction can represented as improper.
In the above case, if you multiply the denominator 5 with the whole number 8 add the numerator 3 to it, you get back 435

Like fractions : Fractions with the same denominator are called like fractions.
Example: 5/7, 3/7. Here we can compare them as (5/7) > (3/7)

Unlike fractions : Fractions with different denominators are called unlike fractions.
Example: 5/3, 9/2. To compare them, we find the L.C.M of the denominator.
Here the L.C.M is 6 So, (5/3)×(2/2) , (9/2)×(3/3)
⇒ 10/6, 27/6
⇒ 27/6 > 10/7

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CLASS 7TH | UNIT 1: NUMBER SYSTEM | RATIONAL NUMBERS | REVISION NOTES

Introduction: Rational Numbers

  • rational number is defined as a number that can be expressed in the form, where p and q are integers and q≠0.
  • In our daily lives, we use some quantities which are not whole numbers but can be expressed in the form of. Hence we need rational numbers.

Equivalent Rational Numbers

  • By multiplying or dividing the numerator and denominator of a rational number by a same non zero integer, we obtain another rational number equivalent to the given rational number.These are called equivalent fractions.
  • ∴andare equivalent fractions.

  • ∴andare equivalent fractions.

Rational Numbers in Standard Form

  • A rational number is said to be in the standard form if its denominator is a positive integer and the numerator and denominator have no common factor other than 1.
  • Example: Reduce.Here, the H.C.F. of 4 and 16 is 4.is the standard form of.

LCM

  • The least common multiple (LCM) of two numbers is the smallest number (≠0) that is a multiple of both.
  • Example: LCM of 3 and 4 can be calculated as shown below:
    Multiples of 3: 0, 3, 6, 9, 12,15
    Multiples of 4: 0, 4, 8, 12, 16
    LCM of 3 and 4 is 12.

Rational Numbers Between 2 Rational Numbers

Rational Numbers between Two Rational Numbers

  • There are unlimited number(infinite number) of rational numbers between any two rational numbers.
  • Example: List some of the rational numbers between −35 and −13.
    Solution: L.C.M. of 5 and 3 is 15.
    ⇒ The given equations can be written asand.
    ⇒ −615,−715,−815 are the rational numbers between −35 and −13.

Note: These are only few of the rational numbers between −35 and −13. There are infinte number of rational numbers between them. Following the same procedure, many more rational numbers can be inserted between them.

Properties of Rational Numbers

Properties of Rational Numbers

Properties of Rational Number

Addition of Rational Numbers

<Addition of Rational Numbers

Subtraction of Rational Numbers

Subtraction of Rational Numbers

Multiplication and Division of Rational Numbers

Multiplication of Rational Numbers
Multiplication and Divison of Rational Numbers

Negatives and Reciprocals

Negatives and Reciprocals

Negatives and Reciprocals

Additive Inverse of a Rational Number

Additive Inverse

Representing on a Number Line

Rational Numbers on a Number Line

Rational Numbers on a Number Line

Comparison of Rational Numbers

Comparison of Rational Numbers
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CLASS 7TH | UNIT 1: NUMBER SYSTEM | INTERGERS | REVISION NOTES

Integers

A whole number, from zero to positive or negative infinity is called Integers. I.e. it is a set of numbers which include zero, positive natural numbers and negative natural numbers. It is denoted by letter Z.

Z = {…,-2,-1, 0, 1, 2…}

Integers on Number Line

On the number line, for positive integers we move to the right from zero and for negative integers move to the left of zero.

Integers Number Line

Facts about how to Add and Subtract Integers on the Number Line

1. If we add a positive integer, we go to the right.

Add a positive integer, we go to the right

2. If we add a negative integer, we go to the left.

Add a negative integer, we go to the left.

3. If we subtract a positive integer, we go to the left.

Subtract a positive integer, we go to the left.

4. If we subtract a negative integer, we go to the right.

Subtract a negative integer, we go to the right.

The Additive Inverse of an Integer

The negative of any number is the additive inverse of that number.

The additive inverse of 5 is (- 5) and additive inverse of (- 5) is 5.

The Additive Inverse of an Integer

This shows that the number which we add to a number to get zero is the additive inverse of that number.

NumberAdditive Inverse
5– 5
14– 14
– 1010
– 66

Properties of Addition and Subtraction of Integers

1. Closure under Addition

For the closure property the sum of two integers must be an integer then it will be closed under addition.

Example

2 + 3 = 5

2+ (-3) = -1

(-2) + 3 = 1

(-2) + (-3) = -5

As you can see that the addition of two integers will always be an integer, hence integers are closed under addition.

If we have two integers p and q, p + q is an integer.

2. Closure under Subtraction

If the difference between two integers is also an integer then it is said to be closed under subtraction.

Example

7 – 2 = 5

7 – (- 2) = 9

– 7 – 2 = – 9

– 7 – (- 2) = – 5

As you can see that the subtraction of two integers will always be an integer, hence integers are closed under subtraction.

For any two integers p and q, p – q is an integer.

3. Commutative Property

a. If we change the order of the integers while adding then also the result is the same then it is said that addition is commutative for integers.

For any two integers p and q

p + q = q + p

Example

23 + (-30) = – 7

(-30) + 23 = – 7

There is no difference in answer after changing the order of the numbers.

b. If we change the order of the integers while subtracting then the result is not the same so subtraction is not commutative for integers.

For any two integers p and q

p – q ≠ q – p will not always equal. 

Example

 23 – (-30) = 53

(-30) – 23 = -53

The answer is different after changing the order of the numbers.

4. Associative Property

If we change the grouping of the integers while adding in case of more than two integers and the result is same then we will call it that addition is associative for integers.

For any three integers, p, q and r

p + (q + r) = (p + q) + r

Example

If there are three integers 3, 4 and 1 and we change the grouping of numbers, then

Associative Property

The result remains the same. Hence, addition is associative for integers.

5. Additive Identity

If we add zero to an integer, we get the same integer as the answer. So zero is an additive identity for integers.

For any integer p,

p + 0 = 0 + p =p

Example

2 + 0 = 2

(-7) + 0 = (-7)

Multiplication of Integers

Multiplication of two integers is the repeated addition.

Example

  • 3 × (-2) = three times (-2) = (-2) + (-2) + (-2) = – 6
  • 3 × 2 =  three times 2 = 2 + 2 + 2 = 6
Multiplication of Integers

Now let’s see how to do the multiplication of integers without the number line.

1. Multiplication of a Positive Integer and a Negative Integer

To multiply a positive integer with a negative integer, we can multiply them as a whole number and then put the negative sign before their product.

So the product of a negative and a positive integer will always be a negative integer.

For two integers p and q, 

p × (-q) = (-p) × q = – (p × q) = – pq

Example

4 × (-10) = (- 4) × 10 = – (4 × 10) = – 40

Multiplication of a Positive Integer and a Negative Integer

2. Multiplication of Two Negative Integers

To multiply two negative integers, we can multiply them as a whole number and then put the positive sign before their product.

Hence, if we multiply two negative integers then the result will always be a positive integer.

For two integers p and q,

(-p) × (-q) = (-p) × (-q) = p × q

Example

(-10) × (-3) = 30

3. The Product of Three or More Negative Integers

It depends upon the number of negative integers.

a. If we multiply two negative integers then their product will be positive integer

(-3) × (-7) = 21

b. If we multiply three negative integers then their product will be negative integer

(-3) × (-7) × (-10) = -210

If we multiply four negative integers then their product will be positive integer

(-3) × (-7) × (-10) × (-2) = 420

Hence, if the number of negative integers is even then the result will be a positive integer and if the number of negative integers is odd then the result will be a negative integer.

Properties of Multiplication of Integers

1. Closure under Multiplication

In case of multiplication, the product of two integers is always integer so integers are closed under multiplication.

For all the integers p and q

p×q = r, where r is an integer

Example

(-10) × (-3) = 30

(12) × (-4) = -48

2. Commutativity of Multiplication

If we change the order of the integers while multiplying then also the result will remain the same then it is said that multiplication is commutative for integers.

For any two integers p and q

p × q = q × p

Example

20 × (-30) = – 600

(-30) × 20 = – 600

There is no difference in answer after changing the order of the numbers.

3. Multiplication by Zero

If we multiply an integer with zero then the result will always be zero.

For any integer p,

p × 0 = 0 × p = 0

Example

9 × 0 = 0 × 9 = 0

0 × (-15) = 0

4. Multiplicative Identity

If we multiply an integer with 1 then the result will always the same as the integer.

For any integer q

q × 1 = 1 × q = q

Example

21 × 1 = 1 × 21 = 21

1 × (-15) = (-15)

5. Associative Property

If we change the grouping of the integers while multiplying in case of more than two integers and the result remains the same then it is said the associative property for multiplication of integers.

For any three integers, p, q and r

p × (q × r) = (p × q) × r

Example

If there are three integers 2, 3 and 4 and we change the grouping of numbers, then

Associative Property

The result remains the same. Hence, multiplication is associative for integers.

6. Distributive Property

a. Distributivity of Multiplication over Addition.

For any integers a, b and c

a × (b + c) = (a × b) + (a × c)

Distributive Property

Example

Solve the following by distributive property.

I. 35 × (10 + 2) = 35 × 10 + 35 × 2

= 350 + 70

= 420

II. (– 4) × [(–2) + 7] = (– 4) × 5 = – 20 And

= [(– 4) × (–2)] + [(– 4) × 7]

= 8 + (–28)

= –20

So, (– 4) × [(–2) + 7] = [(– 4) × (–2)] + [(– 4) × 7]

b. Distributivity of multiplication over subtraction

For any integers a, b and c

a × (b – c) = (a × b) – (a × c)                      

Example

5 × (3 – 8) = 5 × (- 5) = – 25

5 × 3 – 5 × 8 = 15 – 40 = – 25

So, 4 × (3 – 8) = 4 × 3 – 4 × 8.

Division of integers

1. Division of a Negative Integer by a Positive Integer

The division is the inverse of multiplication. So, like multiplication, we can divide them as a whole number and then place a negative sign prior to the result. Hence the answer will be in the form of a negative integer.

For any integers p and q,

( – p) ÷ q = p ÷ (- q) = – (p ÷ q) where, q ≠ 0

Example

64 ÷ (- 8) = – 8

2. Division of Two Negative Integers

To divide two negative integers, we can divide them as a whole number and then put the positive sign before the result.

The division of two negative integers will always be a positive integer.

For two integers p and q,

(- p) ÷ (- q) = (-p) ÷ (- q) = p ÷ q where q ≠ 0

Example

(-10) ÷ (- 2) = 5

Properties of Division of Integers

For any integers p, q and r

PropertyGeneral formExampleConclusion 
Closure Propertyp ÷ q is not always an integer10 ÷ 5 = 2
5 ÷ 10 = 1/2
(not an integer)
The division is not closed under division.
Commutative Propertyp ÷ q ≠ q ÷ p10 ÷ 5 = 2
5 ÷ 10 = 1/2
The division is not commutative for integer.
Division by Zerop ÷ 0 = not defined
0 ÷ p = 0
0 ÷ 10 = 0No
Division Identityp ÷ 1 = p10 ÷ 1 = 10Yes 
Associative Property(p ÷ q) ÷ r ≠ p ÷ (q ÷ r)[(–16) ÷ 4] ÷ (–2) ≠
(–16) ÷ [4 ÷ (–2)]
(-8) ÷ (-2) ≠ (-16) ÷ (-2)
4 ≠ 8
Division is not Associative for integers.
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CLASS 6TH | SOUTH AMERICA: LOCATION, AREA, POLITICAL AND PHYSICAL FEATURES | REVISION NOTES

POINTS TO REMEMBER

  • The Isthmus of Panama joins South America to North America. South America is triangular in shape and a greater part of it lies south of the equator.
  • South America can be divided into four physical divisions—the West Coastal Plains, the Andes Mountains, the Central Plains and the Eastern Highlands.
  • The West Coastal Plains are narrow plains lying between the Pacific Ocean and the Andes Mountains, in the western part of the continent. The Atacama Desert is located here.
  • The Andes are a long stretch of high, young fold mountains that run parallel to the Pacific Coast in the western part of the continent. Mt Aconcagua, the highest peak in South America, and Lake Titicaca, the second highest freshwater lake in the world, are located here. There are also several active dormant volcanoes located here such as Mt Chimborazo and Mt Cotopaxi.
  • The Central Plains are lowlands that lie between the Andes in the west and the Eastern Highlands in the east. The flat plains are formed by the rivers Amazon, Orinoco, Parana, Paraguay and Uruguay.
  • The Guiana Highlands and the Brazilian Highlands form the Eastern Highlands. The two highlands are separated by the river Amazon. These highlands extend in the eastern part of the continent along the Atlantic coast.
  • The Orinoco River, the Magdalena River and the Amazon River are some of the important rivers of South America. Rivers Paraguay, Parana and Uruguay form the La Plata river system. Lake Titicaca, Lake Poopo and Lake Maracaibo are the important lakes of die continent.

IMPORTANT TERMS

Llanos : The grasslands of the Orinoco Basin.
Selvas : The dense equatorial forest of the Amazon Basin.
Pampas : The extensive temperate grasslands of Argentina.

VALUES AND LIFE SKILLS

We must learn not to exploit natural resources and to instead, take care of our environment and the natural resources we have, like the indigenous people in the Amazon Basin

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CLASS 6TH | NORTH AMERICA: CLIMATE, NATURAL VEGETATION, WILDLIFE, MINERAL AND POWER RESOURCES | REVISION NOTES

The Natural vegetation largely depends on climate,soil and the relief features.North America has a wide variety of vegetation. These vegetation belts follow the climatic zones.

Tundra Type  vegetation
In the northern parts of Canada This type of vegetation is found.  Mosses, Lichen and dwarf willows grow. There is not much growth of vegetation only some bright flowering plants grown in short  summer season.

The Coniferous  forests
To the south of Tundra belt in southern Canada lies the Coniferous  forests. These forests consist of trees like pine, spruce and fir. Trees of this region have conical leaves and thick stem.

The Temperate Mixed  forests
Oak, Beach, Dauglas fir and Maple trees are examples of the Temperate Mixed Forests vegetation in Canada and USA. Most of the soft wood industries of Canada are developed in this region.

The Temperate Grasslands
The Temperate Grasslands Of North America are called as Prairies. Only grass grows due to less amount of rainfall. Tall trees are almost absent.

 The Mediterranean Type
The trees of this region are small with shininig leaves and hard stem. Olive, cork, myrtle and oak are the main trees found here alomg with Fruit tree like Oranges, Grapes, Apricots.

The Dry Forests
These forests are also called as Desert Vegetation. In this region hardly any forests are available due to extreme climate and low rainfall. Cactus, thorny bushes are the main vegetation here.

The Tropical rain forests
These forests are around the gulf of Mexico coastal region. The main trees found in this region are palm, Yellow Pine and Cypress. Most of the land of this region is under cultivation.

Warm Temperate forests
These forests  are of mixed coniferous and deciduous foresets. This region consist of the treee like  Oak, Chestnut, Magnolia, Yellow Pine  and Cypress. Yellow Pine trees are very famous in this region.

MINERAL AND POWER RESOURCES

Coal

  • Pennsylvanian Anthracite
  • Appalachian Bituminous
  • Pittsburgh N. Appalachians (Iron and steel Capital of the world)
  • Birmingham S. Appalachians (Pittsburgh of the south)
  • Interior Provinces (Indiana, Illinois, Iowa, Missouri, Kansas, Oklahoma, Arkansas)
  • Gulf Provinces (Texas, Alabama, Arkansas)
  • Rocky Mountain Provinces (Utah, Colorado, Wyoming, Montana, N. Mexico, N. Dakota)
  • Pacific Provinces (Washington, Oregon, California)
  • Alaska (future reserves)

Hydro Electric Project (HEP)

Fall Line (Appalachians) , Rockies, Mississippi Basin, Laurentian Shield, Great Lakes, St. Lawrence, Grand coulee Dam , R. Columbia (Washington) , Bonneville Dam R. Columbia (Washington) , Hoover Dam or Boulder Dam (reservoir L. Mead) R . Colorado, Davis Dam and Parker Dam (R. Colorado in Arizona) , St. Lawrence Seaway with generating stations at Beauharnais, Cornwall, Prescott, Kingston, Montreal, St. Anthony falls (Minneapolis) , Long Sault Rapids (Massena) . Dams along Mississippi and Missouri (Fort peck, Garrison, Fort Randall, Gavin՚s Point) . Tennessee Valley Project on R. Tennessee.

Petroleum and Natural Gas

1. Midcontinental region (Texas, Oklahoma and Kansas)

  1. 1930 Oklahoma City became the heart of American oil industry.
  2. Also a great Natural gas area.

2. Gulf coasts region

  1. (S. Texas, Louisiana, Mississippi and Arkansas)
  2. Extends under the continental shelf of the Gulf of Mexico.

3. Rocky Mountain Regions

  1. Wyoming, Colorado, Montana, N Mexico
  2. Mining difficult and expensive (because of scattered deposits, folding and faulting)

4. Californian Region: Centered at Los Angeles, Long Beach and S San Joaquin

5. Appalachian and Eastern Interior Region (Pennsylvania, Kentucky and Ohio

6. Alaska Region (A pipeline for shipment to USA From Alaska to Valdez)

Iron Ore

  • Lake Superior region (Hematite) e. g. Mesabi (Iron ore is shipped from Duluth)
  • North East region Adirondacks (New York) and Cornwall (Pennsylvania)
  • South East region Birmingham (Alabama) (Red Mountains)
  • Western region Scattered fields at Utah (Iron Mountain) , Nevada, Wyoming, California (Eagle Mountain) Steelworks at San Francisco Los Angeles Pueblo (Colorado) Provo (Utah) Copper
    • Arizona Globe Morenci Largest single copper mine Bingham (Utah) -Montana Butte
    • Nevada and New Mexico (new Producers)

Tin

  • USA is very short of tin and therefore imports and stockpiles large quantities. -American stockpile release drastically affects tin prices Bauxite
  • Due to great bulk of the Bauxite, concentration is due at seaboard Locations. -Mobile (Alabama) -Baton Rouge (Louisiana)

Others

  • Lead Rockies, Ozark Plateau of Missouri, Idaho, Utah, Arizona, and Colorado.
  • Zinc Missouri, Oklahoma, Kansas
  • Tungsten Nevada, Utah, Idaho
  • Molybdenum Leading producer. Climax mine of Colorado is probably the world՚s largest molybdenum mine.
  • Platinum California
  • Mica Largest produces are Eastern Rockies and Appalachians
  • Sulphur Texas (major producer)
  • Silver, Vanadium and Uranium are also found.

Industrial Regions

Southern New England

  • Centered at Boston -Boston (Shipbuilding, Textiles, Shoemaking, Footwear Machinery)
  • Lowell Providence (Woolen Textile)
  • New Bedford (Worsted Textiles)
  • Fall River (Cotton Textiles) -Hartford (Aircraft and Armaments)

Mid Atlantic States

  • Depends upon Pennsylvanian anthracite Iron ore, Coal and oil from Appalachians (Industrial conurbation from New York to Baltimore) Iron and Steel industries, Engineering, electrical goods etc. Pittsburgh Lake Erie region -Iron and steel Region
  • Pittsburgh (Iron Steel capital of the world) , Cleveland (Steel, Wearing apparel) , Wheeling (Steel) , Akron (Rubber) , East Liverpool (Pottery) , Buffalo (Flour milling chemical metal goods)

Detroit Region

  • Detroit Greatest automobile manufacturing region
  • Centered at Detroit, Lansing and Toledo Automobile and related industries

Lake Michigan Region

  • Chicago (Focal point at the convergence of roads and railways from all over the USA) Iron and Steel, Meat Packing, Grain milling, Agricultural machines, Rail Engines and coaches
  • Milwaukee Steel Engineering Textiles -Gary Iron and Steel

Southern Appalachian Region

  • Birmingham Iron and Steel. (The region gets its H. E. P from the Appalachian fall line) .

Eastern Texas

  • Industrial development dependent upon oil. The area has world՚s largest known deposits of Sulphur.
  • Known for Oil, Chemical and cotton Industries.
  • Shift westward of cotton belt has provided raw material and Created markets.
  • Assisted by the construction of Intra coastal waterway running parallel to the coast.
  • Houston Oil refineries, chemical plants, synthetic rubber
  • Dallas and Fort Worth are twin cities lying in this region. Dallas, a major cotton market is known for clothing and fashion. Fort Worth is known for Cattle, aircraft and aerospace. These two cities share the world՚s largest airport and are also major financial centers owing to vast oil wealth.

Other Industrial Cities

  • St Louis Meat Packing, Flour Milling and Agricultural machines
  • Kansas City Agricultural machine, Aircraft, Oil refining
  • Omaha, Cincinnati, Indianapolis, Denver, St. Paul, Minneapolis, and Memphis these places have Flour milling, Meat packing, Cotton textiles, Food processing and other agricultural industries.
  • New Orleans Oil refining, Chemicals and Cotton textiles -San Francisco Oil refining, steel, aircraft engineering, food processing.
  • Los Angeles and San Diego -Oil refining, steel, aircraft engineering, food processing, television
  • Seattle Aircraft, Lumbering, Fish Canning, aluminum smelting.

Canada

Coal

Cape Breton Island, Vancouver Island (Lies in British Columbia and feeds the Sydney Steel Plants) and Alberta.

Hydro-Electirc Projects

  • Vancouver, Duncan, Bridge river, Arrow Lakes, Corner Brook, Kemono, Churchill falls (formerly Hamilton falls) .
  • St. Lawrence Niagara falls -Rapids at Salt Ste Marie -Nipigon River (Port Arthur and Fort William)
  • Winnipeg River -Kitimat scheme (R. Nechaka) Petroleum
  • Prairie provinces of Alberta and Saskatchewan (centered at Edmonton, Calgary and Turner valley) , Grand Bank, Athabasca Tar Sand.
  • Trans Canadian gas pipeline supplies gas from Alberta gas fields to Toronto and Montreal. Iron Ore
  • Knob Lake (Labrador) , Steep Rock (N. of Lake Superior) Baffin Island

Others

  • Copper Sudbury, Flin Flon, Sheridan, Lynn Lake and Coppermine
  • Nickel Sudbury, Lynn Lake, Hope, Thompson
  • Lead, Zinc and Silver Sullivan Mines (British Columbia) . Also in Manitoba and North

West Territories Industries

  1. Lake Peninsula to Montreal -Good Accessibility, Cheap H. E. P American investment Toronto Engineering, Automobile, Chemicals, Textiles, Pulping and Food processing Hamilton (Birmingham of Canada) Heavy engineering and Iron and Steel. Windsor Automobile, Tyre making- Kingston Locomotive
  2. St. Lawrence region Montreal Ship Building, Oil Refining, Paper and Pulp and Food Processing. It is a Leading Grain port. Quebec Marine Engineering, Ship building, Food Processing Ottawa Saw milling, Paper and Pulp
  3. Continental interior (Canadian Prairie) Winnipeg Agricultural, industries, Fur, Dressing textiles Edmonton Oil extraction, Natural gas
  4. Vancouver Lumbering Timber industries Fish canning
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CLASS 6TH | NORTH AMERICA: LOCATION, AREA, POLITICAL AND PHYSICAL FEATURES | REVISION NOTES

POINTS TO REMEMBER

  • North America has been named after Amerigo Vespucci, an Italian explorer. However, Christopher Columbus is credited with the discovery of this continent.
  • The continent lies in the northern and the western hemispheres surrounded by the Arctic, the Atlantic and the Pacific oceans. The Isthmus of Panama joins North America to South America.
  • The United States of America and Canada occupy three fourths of North america.
  • NorthAmerica can be divided into four major physical divisions— the Canadian or Laurentian Shield, the Western Mountain System or Western Cordilleras, the Eastern Highlands or Appalachian Mountains and the Central Lowlands or Great Central Plains.
  • The Canadian Shield is composed of some of the oldest known hard rocks of the world. The surface of the Shield consists of many deep depressions formed by scraping and scouring out by moving ice. These depressions have been filled up with meltwater to form many freshwater lakes such as the five Great Lakes.
  • The Western Cordilleras are a series of young fold mountain ranges which have many active and extinct volcanoes, earthquake-prone regions and hot springs. The Cordilleras consist of several parallel ranges such as the Alaska Range and the Brooks Range. The highest point in North America, Mt McKinley, lies here. .
  • The Appalachians are lower than the Western Cordilleras. The eastern slopes of these highlands are very steep.
  • The edge of the Piedmont Plateau (located at the foot of the Appalachians or the Eastern Highlands) has many waterfalls along its length. It is referred to as the Fall Line.
  • The Great Central Plains have the largest river system in North America—the Mississippi-Missouri river system.
  • North America has several large rivers such as the Mississippi, Missouri, Mackenzie, Nelson, St Lawrence, Hudson, Yukon, Columbia and Rio Grande.
  • Lumbering is an important activity in the coniferous or taiga forests of Canada, carried out by lumbermen or lumberjacks.
  • Lumbering involves several stages of work such as cutting, skidding and hauling.

IMPORTANT TERMS

Gorge : A deep narrow valley with near vertical sides. Intermontane plateau: a plateau surrounded by mountains on all sides.
Lumbering : The cutting down of trees and the processes leading to the manufacture of products like paper, newsprint, synthetic fibres, etc.
Lumberjacks : Workers engaged in lumbering.
Meltwater : Water derived from the melting of glacier ice and/or snow.

VALUES AND LIFE SKILLS

All occupations are important. Every job has dignity and deserves our respect.

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CLASS 6TH | SOUTH AMERICA: CLIMATE, NATURAL VEGETATION, WILDLIFE, MINERAL AND POWER RESOURCES | REVISION NOTES

POINTS TO REMEMBER

  • The climate of South America is influenced by its location, presence of the Andes Mountains, prevailing winds, nearness to seas and oceans, and the impact of ocean currents.
  • The vast continent of South America has a climate that varies from the equatorial climate in most of Brazil, to the desert climate of the Atacama and Patagonian Deserts.
  • Some areas of Venezuela, Guyana, and Brazil also experience tropical climate. There is a small stretch of central Chile which experiences Mediterranean climate. Southern Chile has a maritime climate.
  • Different climates have influenced the natural vegetation found in South America. Forests exist in areas that receive heavy rainfall throughout the year such as the equatorial forests of the Amazon Basin. Grasslands predominate in regions that record maximum rainfall during the summers such as the grasslands in Guyana and Brazil. Deserts exist in areas that receive hardly any rainfall such as the Atacama and Patagonian Deserts. Mountain vegetation grows in the Andes and Mediterranean vegetation is found in central Chile.
  • The wildlife of South America includes several unusual species such as the anaconda, birds such as the egret, rhea, and condor, and animals such as the guanaco, vicuna, and llama.
  • Hardwood trees like mahogany, rosewood, and rubber are found in the selvas. Brazil nuts, balsa, cinchona for quinine, gum, resins, and dyes are other products obtained from these forests. Yerba mate is an important tree that grows in the Eastern Highlands.
  • Rivers like the Amazon, Orinoco, and Parana provide inland water transport. Brazil, Argentina, Paraguay, and Venezuela have developed hydroelectric power projects.
  • South America is rich in minerals ranging from crude oil, copper, diamond, gold to silver. This is what attracted the Europeans to settle in this continent.

IMPORTANT TERMS

Campos : the tropical grasslands in central Brazil.
Gran Chaco : lowland alluvial plain in interior south-central South America.
Armadillo : an animal found in South America with a hard shell made of pieces-Of bone.
Lguana : a large tropical lizard found in South America

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