Day sand Night

Unit 4

Day sand Night

You will learn about

* The sky during the day and night

* Rhythms of the day and night

* Directions

Observe the picture. What do you see?

Day Sky

The Sun

The Sun gives us light and heat. It helps plants grow. The Sun is much bigger than the earth where we live. The Sun looks small because it is far away from the earth. There will be no life on earth if there is no Sun.

Do you know?: The sunlight takes around 8 minutes to reach the earth.

Shadow

When an object does not allow light to pass through it, a dark area is formed. This is called a shadow.

Stand with your back to Sun. Look at the ground in front of you. What you see is your shadow. Find out if your shadow moves with you.

* Observe the things around you that make shadows and share it with your friends.

Have you noticed that the size of your shadow changes? Observe your shadow in the morning, afternoon and evening and find out its size.

Night Sky

Let Us Discuss

Can we see in the dark? We need light to see things. Observe the pictures. How is the night sky different from the day sky?

The Moon

In the night sky, we can see the moon, many stars and clouds too. As you know, the moon does not have light of its own. It gets its light from the Sun.

Phases of the Moon

Let Us Discuss

Does the moon look the same every day? Observe the moon in the sky every night for fifteen days and find out.

The moon appears to change shape every night. On the night when we see it in its complete form, it is called the full moon (Pournami).

On the night when we cannot see the moon at all (even when the sky is clear), it is called the new moon (Amavasai).

Many festivals are celebrated based on the phases of the moon - e.g., Eid, Mahalaya Amavasai.

Do you know? : Neil Armstrong was the first man to step on the moon.

The Stars

There are countless stars in the sky. The Sun is the nearest star. The stars shine during the day too, but we cannot see their light because the Sun is much brighter than the other stars. We see that a group of stars appears to form a pattern in the sky. Have you seen any star patterns?

Do you know? The position of the pattern of stars helped people to know when to sow and harvest crops. They also helped to people find directions during travel.

Match the following.

a) Sun         - a dark area that travels with me     

b) Stars       - does not have its own light

c) Moon      - form patterns

d) Shadow   - helps plants grow

Answer:

a) Sun         - helps plants grow

b) Stars       - form patterns

c) Moon      - does not have its own light

d) Shadow   - a dark area that travels with me

Rhythms of Day and Night

Day and night follow each other in a rhythmic way. Most animals and plants are active during the day and sleep at night. Some plants close their leaves by evening, e.g., Rain tree (Thoongu-Moonji Maram). However, some animals are active at night. The bat, owl, wild big cat, mouse, wolf, cockroach and firefly are examples of animals that are active at night.

They are active at night to:

* Catch other animals wandering at night for their food

* Avoid animals that eat them during the day

* Avoid the heat of the day

They have:

* Big eyes (owl, cat)

* A sharp sense of smell (mouse, dog)

* Good hearing (bat)

Do you know?

Bats use sound waves to fly and hunt. Owls can see what is behind them by rotating their heads almost fully.

Most flowers bloom in the morning. However some flowers bloom at night. Examples are Jasmine, Water lilies, Tuberose, Cactus flower, Datura flower. Many of them have a lovely fragrance. Many are white in colour though some have attractive colours.

Do you know?

The Bethlehem Lily (Nishagandhi) is called the “Queen” of the flowers that bloom at night.

Identify and tick (✓) the animals that are active at night.

Directions 

Front, back, right and left tell us where things are, based on a reference point. North, South, East and West tell us where places and things are, based on the position of the Sun. They are called directions. Directions help us reach a place without getting lost.

The Sun appears to rise in the East and set in the West. Now stand facing the Sun in the morning (i.e. East). Behind you is West. To your right is South. To your left is North.

Observe the picture given below. In the centre is Meera. To her South are the flower pots, to her North are the rocks, to her East is the flower cart and to her West is the tree trunk.

In your school, identify the eastern direction by finding out where the Sun rises. Ask your teacher to help you. Then find the direction in which the following are situated - water tank, flag post, playground, toilet, kitchen, gate and water tap. Tabulate your answer.