4. Water exists in 3 states: solid,
liquid and gas.
In ice and snow, water is in a
solid state.
In rivers, lakes, seas, oceans
and groundwater, it is in a liquid
state.
In the air, water is in a gaseous
state, called wáter vapour.
5. -When we warm solid water, it changes its state to liquid or it melts. This is called MELTING.
-When we cool liquid water, it changes its state to solid or it freezes. This is called
SOLIDIFICATION.
-When we warm liquid water, it changes its state to gas or it evaporates. This is called
EVAPORATION.
-When we cool water vapour, it changes its state to liquid or it condenses. This is called
CONDENSATION.
6. WATER CYCLE
The Earth has a limited amount of water. The same water keeps
going around and around the planet in a process called the water
cycle.
7. The sun warms up water in rivers, lakes, seas and oceans and it
begins to evaporate.
Water vapour goes into the air.
When the vapour cools, it condenses and forms clouds..
When clouds are too heavy, the water falls as rain, snow or
hailstones. This is called precipitation.
The cycle starts again. It never ends.
8. WATER ON EARTH
The fresh water comes from rain, snow and ice. You find it in lakes, rivers,
ponds and groundwater. Only 1% of all water on Earth is fresh water.
Most of the water on Earth is salt water. Salt water is in seas and oceans.
9. A person can live weeks without food, but
A person can live weeks without food, but
only about three days without water!
only about three days without water!
26. QUIZ
1. Solid, liquid or gas?
a. Rain
b. Ice c. Ocean
d. Water vapour
e.When water vapour condenses, it is ….
f. When water freezes, it is ….
g. When ice melts, it is ….
h. When water evaporates, it is …
2. Water Cycle. Complete the sentences:
The …. warms water in rivers, lakes, seas and oceans. The water …. and
goes into the air in the form of water …. . The water vapour …. and forms
clouds. When the clouds get too heavy, the water falls as …., snow or
hailstones. The water returns to …., lakes and seas. The …. …… never
ends.
3. Answer the questions:
a) What are the 2 elements water is made of?
b) What are the three characteristics of water?
c)Where can we find fresh water on the Earth?
d) Where is salt water on the Earth?
27. ANSWERS
1. a. liquid b. solid c. liquid d. gas
e. liquid f. solid g. liquid h. gas
2. sun; evaporates; vapour; condenses; rain; rivers; water cycle.
3. a) hydrogen and oxygen
b) It has no smell, no colour and no taste
c) lakes, rivers, ponds and groundwater.
d) seas and oceans.
e) Free answers (for example, turn the taps off; have short showers;
fill the washing machine).
Notas del editor
This week we are going to look at water and how important it is.