`Gases Lighter and Heavier than AirBonnie Anderson                Libby School Annex                               5338 S. Loomis                               Chicago IL 60609                               (312) 535-9350Objective: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 lineStrategy: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. MilneWinnie the Pooh, story adaptations and song book, Walt Disney ProductionsStorybook Science:Innovative Hands-On Science In Your Primary Classroom, R.S. Cichowski`