Kids Learning Science

 

3rd Standard Science Term - I

States of Matter

  Matter  

Teacher : Leela, look at the picture and list out the things you see in it.

Leela : Yes madam.  Sun, river, boat, house, tree, car, birds, ... 

Teacher :  Very good.  There are many things in this picture.  Some of them are natural and some are man-made.

You can see a number of things around you.  Everything you can see and touch is made up of matter.  Anything that occupies space and has mass is called matter.

  More to know  

What is mass?

Mass is a measure of how much matter is in an object.

• The air we breathe, the food we take, and the water we drink all have matter in them.

Do you know that even you are made up of matter?

The space occupied by an object is called its volume.

  2.1. States and properties of Matter  

Matter can exist as solid, liquid or gas.

     Salid               Liquid             Gas

• rigid             
• fixed shape         
• fixed volume              

     

• not rigid
• no fixed shape
• fixed volume

• not rid
• no fixed shape
• no fixed volume

SOLIDS

  Let us Try  

Press a wooden pencil.  Is the pencil hard? Yes/No.

Solids are things that have a definite shape and volume.  They occupy a fixed space.  The particles in solids are packed very tightly.  So they cannot move freely.  Their shape can be changed only when we break or cut them.

LIQUIDS

  Let us Do  

1. Place four 1L bottles of different shapes on the table.

2. Take a bucket with water.

3. Call one child to hold the empty bottles and the other to fill water into them using a paper cup.

4. Ask the other children to fill the table as given below.

                            Bottle        Bottle        Bottle        Bottle

                               1                 2                3              4

Number of 

cups used

Shape of 
bottle (Draw)

Did each bottle need the same number of cups to get filled?

We can see that water takes up the same space in each bottle and the shape of the water is same as the shape of the bottle.

Look at these pictures

Here we can see that the shape of the liquid is determined by the shape of the container.

Liquids are the things that do not have a definite shape but occupies space.  They have a definite volume.  They take the shape of the container in which they are filled.  The water moves from one place to another.  This is because the matter in liquid are loosely packed.  So, liquids can flow freely.

  Let us Touch and Feel   

Different types of liquids are placed in separate containers.  Students are allowed to touch and feel every type of liquid.  They are asked to tell the type of the liquids on the basis of their stickiness/concentration.

GASES

When a perfume is sprayed or an agarbatti is lighted, the fragrance spreads all around the room.  How?

The matter in gases are very loosely packed.  So they can move around freely in all directions.  Hence, gases do not have a definite shape and do not occupy a definite space or volume.

Most of the gases are colourless.  But when they are mixed with solid particles they show distinct colours.

  2.2. Change in States of Matter  

Matters change their state as the temperature changes.  Solid changes into liquid and liquid changes into gas on heating.  Gas becomes liquid and liquid becomes solid on cooling.

Melting

Change of solid into liquid on heating is called melting.  For example, if ice (solid) is heated, it will change into water (liquid).

Evaporation

Change of liquid into vapour on heating is called Evaporation.  For example, if water is heated, it will change into steam.

Freezing

Change of liquid into solid on cooling is known as freezing.  For  example, water (liquid) poured in ice-tray and placed in the freezer (fridge), gets cooled and becomes ice (solid).

Condensation

Changes of gas into liquid on cooling is called condensation.  for example; clouds (gas) on cooling condense and fall as rain (liquid)

  Let us Observe  

Take a balance.  Keep an air filled football in one plate and on empty football in another plate.  What happens?

Air filled ball goes down.  It is because air has mass.

Do you

Air is a mixture of gases.  You can feel the presence of air when the wind blows.

  Let us Prepare - Anchor chart  

1. Cut a chart into three pieces each of 15cm x 10cm.

2. Write the properties of solid, liquid and gas in separate sheets.

3. Draw pictures related to the points. 

4. Design the sheets with colourful borders.

5. Paste all the sheets in a large chart paper.  Your anchor chart is ready.

Hang it on the wall.

  Let us Understand  

✔  Keep a stone on the floor.  Does it move by itself?

✔  Pour a mug of water on the floor.  Does the water flow? Does it flow in one direction?

✔  Take an air filled balloon.  Prick it with a needle.  Does the air rush out?

✔  Fill an open vessel with water.  Press the surface of the water with your hands.  How do you feel?

2. 4. Materials Used / Not Used for Heating

Fuels 

• Paper, firewood, dried leaves and charcoal can be burnt.
• Liquids like kerosene, petrol and diesel also burn on heating.
• Domestic gas burns and helps in cooking.

Substances when burnt give out heat.  But in some substances, the heat released is very low.  Thus, these are not used for heating purpose.

Substances that give out more heat while burning are used for heating purpose.  These substances are called fuels.

Solid fuels

Gaseous fuels

Liquid fuels