1. WELCOME
SUBMITTED BY
PRAVASINI BISWAL
ROLL NO -16
ROJALIN SAHOO
ROLL NO -19

2. INTRODUCTION
• Can you say few things you can change
around you ?
• Did you realise that so many changes are
taking place around you all the time?
• Can some of the changes be grouped
together?
• Can all the changes always be reversed?

3. EXPLANATION
• Let us perform some day to day life activities.
Take a balloon and blow it. Take care
that
it does not burst. The shape and size of the
balloon have now changed. Now let the air
escape the balloon.

4. IMAGE OF BLOWING A BALLOON

5. Activity - 2
• Now take a piece of paper and fold it. change
the shape of the paper into a toy aeroplane .
Now you have changed the shape of the paper
into a toy aeroplane.
• Now again unfold the paper.

6. IMAGE OF PAPER AEROPLANE

7. ACTIVITY- 3
• Now take some dough and make a ball.
• Try to roll out a roti.
• Now again change it back into a ball of dough
again.

8. OBSERVING THE THREE ACTIVITIES
• Now think about the three changes you
observed in activity 1,2,3.Now tell what do
they have in common ?
• Was it possible to get the ballon back to its
origional shape and size ?
• Was the size of the paper same as before and
after making an aeroplane ?
• Was it possible to get back the ball of dough
again ?

9. CONCLUSION FROM THE THREE
ACTIVITIES
• In each of the three activities ,is it possible to
get back to the materials with which we
strated our activity ?
The answer is yes.It means that the
changes ocuuring in these activities can be
reversed.
So, the chanes in which we can again get
back the origional substanse are called
reversible changes.

10. REPEAT OF THE ACTIVITY-1 WITH A
DIFFERENCE
• Now take the same balloon again which you
already used in activity 1.
Blow it to its full size and tie its
mouth with a string tightly.
Prick it with the pointed tip of your
pencil. Then now what is the result . It bursts.

11. IMAGE OF A BURSTING OF A BALLOON

12. REPEAT OF ACTIVITY-2
• Take the same piece of paper, which you used
in activity 2.Draw an aeroplane on it and cut
along its outline.

13. IMAGE OF CUTTING OF A PAPER

14. REPEAT OF ACTIVITY- 3
• Now roll out a roti from the ball of dough
again and bake it on a tawa .

15. IMAGE OF BAKING A ROTI

16. OBSERVATION OF REPEATING
ACTIVITIES
• Now tell was it possible to get the ballon back
to its origional shape and size ?
• Was the size of the paper Same as before and
after making an aeroplane ?
• Was it possible to get back the ball of dough
again ?

17. CONCLUSION OF REPEATING
ACTIVITIES
• Now it is sure that all the three repeating
activities are not reversed. That is in these
changes we can not again get back the
origional substances.
So, the changes in which we can not
get back the origional substances again are
called reversible changes.

18. ONE OF THE VIDEO INVOLVING REVERSIBLE
AND IRREVERSIBLE CHANGES

19. REVERSIBLE CHANGE
• The changes in which we can again get back
the origional substances are called reversible
changes.
• EXAMPLES - Boiling of water.
Melting of ice.
Blowing of ballon.
folding of paper.

20. IRREVERSIBLE CHANGES
• The changes in which we cannot again get
back the origional substances are called
irreversible changes.
EXAMPLE – Cutting of paper.
Bursting of balloon.
Making of chapati.
Formation of curd from milk.

21. SUMMARIZATION
• THE CHANGES IN WHICH WE CAN AGAIN GET
BACK THE ORIGIONAL SUBSTANCES ARE
CALLED REVERSIBLE CHANGES.
• THE CHANGES IN WHICH WE CANNOT AGAIN
GET BACK THE ORIGIONAL SUBSTANCES ARE
CALLED IRREVERSIBLE CHANGES.

22. EVALUATION
 A drawing sheet changes when you
draw a picture on it . Can you reverse
this change ?
 You accidentaly dropped your
favourite toy and broke it. This is a
change you did not want. Can this
change be reversed ?
 To walk through a waterlogged area ,
you usually shorten the length of your
dress by folding it. Can this change be
reversed ?