Gases Lighter and Heavier than Air

Bonnie Anderson                Libby School Annex
                               5338 S. Loomis
                               Chicago IL 60609
                               (312) 535-9350

Objective:

This lesson was designed for students in grades 2-4.  
The students will be able to understand and demonstrate that there are gases 
that are lighter (less dense) and heavier (more dense) than air. 

Materials Needed:

Winnie the Pooh storybook, Jensen bars, Helium balloons (already filled), 
Balloons, Vinegar, Baking soda (about 2 Tbs. for each child, wrapped in a piece 
of light weight paper), Plastic drink bottles (12-16 oz. size), Small (4") 
pictures of Winnie the Pooh, 12" lengths of fine monofilament line

Strategy:

Tell children the story "We are Introduced" from Winnie the Pooh.  Discuss how 
Pooh got up in the air and ask if the children would like to try to make Pooh 
Bear fly.  Distribute empty balloons, monofilament and pictures of Pooh.  Let 
the children try to make Pooh fly and ask what they observe.  Why can't Pooh 
fly?  Ask for suggestions for how to help Pooh. 

Distribute monofilament and pictures of Pooh, then bring out helium-filled 
balloons.  Let the children now try to help Pooh fly, but try to control his 
flight so he doesn't end up on the ceiling!  Record the children's observations.  
They should be able to conclude that a helium-filled balloon is lighter (less 
dense) than an air-filled balloon, and being lighter than air will help a 
helium-filled balloon to float up. 

Tell the children that they can make another gas to fill a balloon.  Do not tell 
them that the gas will be heavier (more dense) than air.  Distribute the plastic 
bottles filled 2/3 with vinegar, paper packages of 2 Tbs. baking soda, and empty 
balloons.  Demonstrate how to fill their balloons with gas -- place the paper 
folded with the baking soda in it into the bottle, then put the balloon over the 
lip of the bottle.  As the paper unfolds and exposes the baking soda, the 
balloon fills with gas.  Tie the balloon off when it is full.  As the children 
compare the balloons they have filled, they will find that their newest balloon 
is heavy compared to both other balloons.  Identify the gas they made as carbon 
dioxide.  Let the children work in groups of 3-4 with Jensen bars to compare 
their balloons.  Record their observations.  They will discover that carbon 
dioxide-filled balloons are much heavier than air-filled balloons.  Children 
should be able to conclude that carbon dioxide is heavier (denser) than air. 

Performance Assessment:  

All children should be able to verbalize that not all gases are the same weight, 
that some gases are lighter (less dense) and some heavier (more dense).  Some 
children will be able to name the gases helium and carbon dioxide and to 
indicate which is more and less dense compared to air and to each other. 
 
Children can draw pictures of Winnie the Pooh holding each balloon.  The 
placement of the balloons in relation to Pooh indicates the understanding of the 
concept of gases lighter and heavier than air. 

References:

Winnie the Pooh, A.A. Milne
Winnie the Pooh, story adaptations and song book, Walt Disney Productions
Storybook Science:Innovative Hands-On Science In Your Primary Classroom, R.S. 
Cichowski