Measurement
We need to measure different things in our daily life like length of objects, height, weight (fruits, vegetables, etc.) quantity of milk, water and so on.
Measurement of Length
In early days, people used body parts to measure lengths.
Cubit Hand span
The metre is what we normally use for measuring lengths. Smaller lengths an measured in centimetres. Metre is written as m and centimetre as cm.
Measurement of Mass
Mass tells us how heavy or light an object is. We use weighing scales to find the mass of an object.
Just as we use metre for measuring length, we use kilogram for measuring mass. Smaller weights are measured in grams. Kilogram is written as kg and gram is written as g.
Measurement of Capacity
Capacity of a container is the amount of liquid it can hold. Litre is the commonly used unit for measuring capacity. Smaller units are measured in milliliters. Litre is written as I and millilitres as ml.
Some Other Units of Measurement
In everyday life we also need to measure things that do not involve length, mass, and capacity. Time and temperature are two such examples. Time is measured in seconds. The measurement of hot or cold of an object is called temperature. Temperature can be measured with the help of a thermometer.
Which of the following is a unit for measuring length?
(a) Metre
(b) Litres
(c) Millilitres
(d) Kilogram
(e) None of these
Answer: (A)
Explanation
For measuring length we normally use metre.
Which of the following tells us how heavy an object is?
(a) Mass
(b) Volume
(c) Length
(d) Temperature
(e) None of these
Answer: (a)
Explanation
Mass tells us how heavy or light an object is.
Mars has a lower gravity than Earth, therefore a person weighing 100 kg (220 pounds) on Earth would only weigh 38kg (84 pounds) on Mars.
Only one third of the energy in burning coal reaches the consumer as electricity.
If 10,000 schools turned off their lights for one minute it could save $81,885.
Force: It is pull or push acting on an object.
Friction: Frictional force opposes the motion of a moving object.
Work: Work is said to be more... 
Introduction
Living things on the earth are mainly divided into two major groups, the plant kingdom and the animal kingdom.
Plant Kingdom Animal Kingdom
The plant kingdom comprises of all the green plants present on the land, water and even those which are non-green in colour. The green colour of the plant is due to the presence of chlorophyll, which aid in photosynthesis. Nature has a wide variety of plants. Each variety has its own uniqueness. We see most of the plant that are green. But there are plants which has coloured leaves. Flowers of some are huge, while some have tiny one. Yet another group doesn't have any flower at all. Some plants have thorns while some are soft, delicate, beautiful and great to smell. We can also see plant life in and on water. Some plants live in dry places, while others need maximum rainfall.
Plant as Autotrophs
Auto means self and trophos means nourishment. Autotrophs are living organisms which can make their own food. They make their food by taking water and minerals from the soil, carbon dioxide from the atmosphere and with the help of sunlight. Algae, some bacteria and large trees belong to this category. This mode of nutrition is called autotrophic nutrition. All green plants can make their own food. They are also known as producers.
Plants as Autotrophs
Sun is the ultimate source of energy for all living organisms. Autotrophs can capture the energy of the sunlight to synthesize food. It is a unique process. The survival of almost all living organisms directly or indirectly depends on the food made by the plants. Autotrophs are fundamental to all in the food chains. All animals, almost all fungi, as well as most bacteria and protozoa, depend on autotrophs for the energy and raw materials.
Look at the following figure of coleus plants.
Coleus plant
Coleus plant obtain its food by which one of the following process?
(a) Evaporation
(b) Photosynthesis
(c) Transpiration
(d) All of these
(e) None of these
Answer: (b)
Which one of the following cannot perform the process of photosynthesis?
(a) Wheat plant
(b) Cactus plant
(c) Peepal tree
(d) Hyena
(e) None of these more... 
Photosynthesis
Photosynthesis is the process by which plants make their own food. It the process of converting carbon dioxide into organic compound, especially sugar using water and sunlight. Oxygen is a by-product of this process. Photosynthesis is vital for life on earth, as it maintain the normal level of oxygen in the atmosphere. All life depends on photosynthesis directly as a source of energy or indirectly as the ultimate source of the energy in their food. Photosynthesis is also the source of carbon in all the living form. Most of the plants have green pigment called, chlorophyll, in their leaves. Chlorophyll gives the green colour of the leaf, helps in photosynthesis. It is the chlorophyll that helps the plants to trap the energy from the sunlight for making their food. Oxygen, which is produced during photosynthesis is essential for all living organisms for their survival. In the absence of photosynthesis life would be impossible on the earth.
Air enters plants through which part?
(a) Stem
(b) Stomata
(c) Fruit
(d) Flower
(e) Root
Answer: (b)
The food, synthesized by the plants in the process of photosynthesis, is stored as ____.
(a) Vitamins
(b) Water
(c) Starch
(d) Both (a) and (c)
(e) None of these
Answer: (c) 
Respiration
Like all living organisms, plants also go through the process of respiration. This process is essential, as it provides energy and the carbon escalation for growth and maintenance. Plants consume about 25 - 75% of all the carbohydrates produced in photosynthesis.
Sugar + Oxygen 
Carbon dioxide + Water + energy.
Plants, like other living things use atmospheric oxygen to breakdown glucose (food produced in photosynthesis) into carbon dioxide and water for the release of energy. This energy is used for its growth and maintenance. In plants, all living cells of root, stem and leaf take in oxygen independently and give out carbon dioxide and water. Hence in plants, there is little transport of gases, from one part to another, occurs Respiration in plants occur at a much slower rate as compared to animals. 
Aquatic Plants
Aquatic plants are those which live in or on the water. Aquatic plants are also called hydrophytic plants. These plants have evolved special features like air sacs for flotation, increased number of stomata, smaller feathery and specialized roots to take in oxygen. Aquatic plants are of three main types.
Floating Plants
These plants are like sponge. There are numbers of empty spaces throughout their body, which is filled with air. This makes the plant light enough to float in the water. For example, duckweed, water hyacinth.
Water Hyacinth
Fixed Plants
These plants have roots fixed to the mud at the bottom of the pond. They have thin, long, hollow and very flexible stem. The plants have broad and flat, plate like leaves with waxy coating on the surface. Stomata are found on the upper surface of the leaves. For example, water lilies and lotus.
Lotus Plant
Underwater Plants
These plants live and grow under water. Their roots fix the plant to the muddy soil. They have narrow thin leaves with no stomata. The leaves absorb carbon dioxide and oxygen directly through their surface. The stems are flexible and have air spaces. For example, tape grass, hydrilla and pond weed.
Pond Weed
What are the aquatic plants?
(a) The plants which grow in water
(b) The plants which grow in desert
(c) The plants which grow in plain
(d) The plants which grow on mountains
(e) All of these
Answer: (a)
Lemna, Eichhornia, Wolffia, Pistia are example of which type of hydrophytes?
(a) Fixed hydrophytes
(b) Floating hydrophytes
(c) Under water hydrophytes
(d) Both (a) and (b)
(e) None of these
Answer: (b) 
Non-Green Plants
Plants which do not have chlorophyll are called non-green plants. They cannot make their own food and usually absorb food from other plants, dead animals or stale food. One type of non-green plant is fungus. Mushroom, toadstools and mould are also example of non-green plants.
Non-Green Plant
Fill in the blank with the appropriate answer.
Non-green plants have ____ type of nutrition.
(A) Autotrophic nutrition
(B) Heterotrophic nutrition
(C) Symbiotic nutrition
(D) All of these
(E) None of the above
Answer: (b)
Name a non-green edible plant that can't prepare their own food but provide us with high nutrition.
(A) Mycorrhizal
(B) Yeast
(C) Mold
(D) Mushroom
(E) All of the above
Answer: (d) 
Terrestrial Plants
Plants that grow on land are called terrestrial plants. Terrestrial plants are of different types depending on the condition they grow in.
Plants on Mountains
Plants on mountains and hills are tall, straight and have slopping shape to make the snow fall off easily. They are usually flowerless and have cones with seeds inside them. The leaves are needle like with waxy coating. For example, fir, deodar, pine, cedar, small flowerless plants like ferns, lichens and mosses etc.
Pine tree Deodar tree Lichens
Plants in the Plain
These plants grow in plain, flat, surface of the earth. Trees have several branches and leaves. Many of these plants grow in warmer climate of the plains and shed most of their leaves in autumn. Example, Neem, Peepal, Ashoka and Mango.
Mango tree Pipal tree Ashok tree
Evergreen Plants
The evergreen plants of the plain are those which grow in hot and wet climate.
Example, Tea, Coffee, Rubber.
Tea Plants Coffee Plant Rubber Plant
Plants in Deserts
Desert is a place with hot weather, very little water and scanty rainfall. Plants growing in these places are called desert plants. These plants develop certain features that help them to survive the harsh conditions of the desert. Roots are spread out just under the surface of the soil to catch the smallest amount of water. These plants more... | more...
LEARNING OBJECTIVES
This lesson will help you to:—
 
Here, each square is of side 1 unit.
Perimeter of shaded region
= 2 units + 5 units + 4 units + 2 units + 2 units
+ 3 units = 18 units
= Sum of the sides of the square
= 3m + 3m + 3m + 3m or
\[=4\times 3m=12m\]
Thus, perimeter of a square = 4 x side
Perimeter of a rectangle is the sum of the length of its sides.
Perimeter of rectangle in fig. 4
= sum of the sides of the rectangle
\[=3m+10m+3m+10m\]or
\[=(3m+3m)+(10m+10m)\]
\[=(2\times 3m)+(2\times 10m)\]
\[=2\times (3m+10m)\]
\[=2\times (13m)=26\text{ }m\]
Thus, perimeter of a rectangle = 2 x (length + width)
Perimeter of a circle is the distance around the circle.
Also, perimeter of a circle is known as circumference of it.
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