Science - Teachers Sri Lanka

Competency 3.0 : Use of chemical changes suitable to fulfil necessities of life
Competency level 3.9 :
Produce a gas - Examine its properties.
Time : 120 mts.
Copyright © 2007 National Institute of Education - Sri Lanka. All rights reserved.
Quality inputs : • A baloon filled with H 2
gas, according to instructions given in
annex 3.9.1. and an empty baloon.
• Three copies of article on instructions for exploration given in
annex 3.9.2
• Work stations arranged accordind to instructions given in
annex 3.9.3
• Demy papers and pastel
Teaching learning
process :
Step 3.9.1 : • Take the baloon filled with H 2
gas, to the class. (do not
mention that it contains H 2
gas)
• Give the other baloon to a student and instruct him to blow into
it so that it is of the same size as the H 2
filled baloon and tie it.
• Let the students predict as to what would happen when the
two baloons are released from hand, direct them to observe.
• Lead a discussion highlighting the following points.
• Both baloons contain the same volume of gas.
• One baloon contain H 2
gas.
• The other baloon has expired air.
• H 2
gas is less dense than normal air, as a result the baloon
went up.
• Expired air is more dense than normal air, as a result the
baloon went down.
• Different gases have different physical and chemical
properties.
(15 mts)
Step 3.9.2 : • Devide the class into three groups.
• Provide the groups with instrutions for exploration, demy and
pastal.
• Assign the tasks and engage the groups in exploration.
• Prepare them to present their findings to the class.
(60 mts.)