Class 4 Science Lesson 8

Exercise

1.Write “True” for the correct sentences and “False” for the incorrect ones:

a) About 60 percent of the earth’s surface is covered by water.
👉 False (It is about 71 percent.)

b) The surface of the earth is the same everywhere.
👉 False

c) The shape of the earth is not completely spherical but is slightly flat at the poles and bulged towards the equator.
👉 True

d) The earth is tilted slightly in its orbit.
👉 True

e) Atmosphere is made up of air, water vapor and dust particles.
👉 True

f) The lithosphere includes the hydrosphere.
👉 False (Lithosphere is land; hydrosphere is water.

2.Choose the right option from the options given below:

a) Whose shape resembles the shape of the earth?
👉 ii. orange

b) Which of the following is the driest landform on earth?
👉 iii. desert

c) Which of the following helps living things to breathe?
👉 ii. air

d) Which of the following statements is true for the Earth’s atmosphere?
👉 i. Atmosphere is a mixture of gases.

3. Answer the following questions:

a) What type of land is found in the Terai region of Nepal?

👉 Terai region has flat and fertile land called plains.

b) What is the reason for the lack of vegetation in the mountains?

👉 The tall mountains are always covered with snow and have less vegetation because of the cold climate.

c) Write the names of the different surfaces of the earth that you have seen.

👉 The surfaces of the earth include plains, hills, mountains, valleys, deserts, and forests.

d) Write any two differences between mountains and hills.

👉 Mountains are taller and covered with snow, while hills are smaller and not usually covered with snow.

e) What is a hydrosphere? What forms does it cover?

👉 Hydrosphere is the part of the earth covered with water, including rivers, lakes, seas, oceans, ponds, springs, and frozen water like snow.

f) What is the atmosphere?

👉 Atmosphere is the layer of air surrounding the earth.

g) What is the atmosphere made of?

👉 The atmosphere is made of air, water vapor, dust particles, and gases like nitrogen, oxygen, and carbon dioxide.

Weather

Exercise

1. Fill in the blanks with the matching words from the list given below: 

Plans, Travel, Changes, Cumulonimbus, Cirrus, Paddy plantation

a) The weather changes continuously.

b) Weather forecast helps in making plans.

c) The weather is clear when there is cirrus cloud in the sky.

d) It rains heavily when there is cumulonimbus cloud in the sky.

e) Paddy plantation is done in the rainy season.

2. Choose the correct answer from the given option:

a) Which of the following precautions should be taken when lightning strikes?

👉 iii. Electrical equipment should be turned off.

b) Which of the following weather has the characteristics of low atmospheric temperature?

👉 i. cold

c) Which of the following is difficult to do on a foggy morning?

👉 i. to drive a vehicle

d) Which of the following clouds is found only in the upper part of the atmosphere?

👉 iii. Cirrus

e) Which of the following clouds falls uniformly in the sky?

👉 iii. Nimbostratus

3. Answer the following questions:

a) Define weather.

👉 Weather is the state of the atmosphere of a certain place at a certain time.

b) What is meant by weather forecast?

👉 Weather forecast is the prediction of weather conditions for a future time.

c) Why is the weather forecast so important?

👉 Weather forecast helps people plan daily activities, protect themselves from natural disasters, and helps in farming and traveling.

d) How many types of clouds are there and what are they?

👉 There are four types of clouds: Cirrus, Cumulus, Stratus, and Nimbus.

e) Distinguish between Cirrus and Stratus.

👉 Cirrus clouds look like bird feathers and appear in clear weather, while Stratus clouds are dark gray, close to the ground, and bring long rain.

f) What means of communication are used in weather forecasting?

👉 Television, radio, newspapers, and mobile phone apps are used for weather forecasting.

Natural Disaster

Exercise

1.Tick (✔) if the following statements are true and cross (X) if they are false:

a) Natural calamities invite disaster.
👉 True

b) Infectious diseases spread due to floods.
👉 True

c) Electrical appliances should be turned off in case of a hurricane.
👉 True

d) We should wear light clothes during cold waves.
👉 False

e) In case of fire, we should jump out of the window.
👉 False

2.Tick (√) the correct option:

a) Which of the following is the cause of the flood?
👉 i. continuous rain

b) Which of the following activities is suitable for the prevention of landslides?
👉 i. terraced farming

c) What should be done in case of a sudden cold wave?
👉 ii. stay inside the house

d) In case of fire, which numbers should be called?
👉 i. 101

e) Which of the following is the effect of a hurricane?
👉 iii. toppling of tall trees

3. Answer the following questions:

a) What is a flood?

👉 Flood is the increase in the amount and speed of water flowing in rivers and streams, usually during the rainy season.

b) State the causes of flood.

👉 Causes of flood are continuous rain, excessive melting of mountain snow, bursting of glaciers, and landslides blocking rivers.

c) What measures should be taken to prevent landslides?

👉 To prevent landslides, plant trees, practice terrace farming, avoid cutting trees on slopes, and control grazing.

d) Why are there less landslides on a slope planted with trees?

👉 Tree roots bind the soil, making it compact and less likely to slide.

e) How does a flood cause the spread of contagious disease?

👉 Flood waters carry dead animals and waste, which decay and spread diseases.

f) What is a cold wave?

👉 Cold wave is a seasonal disaster caused by extreme cold air and thick mist blocking sunlight.

g) What are the effects of a cold wave?

👉 Cold waves cause diseases, make grazing difficult, freeze water pipelines, and increase fuel consumption.

h) What measures should be taken to protect ourselves from cold waves?

👉 Stay warm indoors, drink hot liquids, wear thick clothes, stay informed via news, and take care of children and elderly.

i) What are the safety precautions to be taken in case of a hurricane?

👉 Stay indoors, secure windows, avoid electric poles, take shelter, avoid panic, and protect from flying debris.

j) When Rita was returning home from school, her neighbor’s house was on fire. In that case, what measures should be taken to prevent additional damages?

👉 Call the fire control department, try to put out the fire safely with water or extinguisher, avoid panic, and stay clear of the fire.