GROUP SIZE: Large or Small
TIME: 30 minutes
TYPE OF ACTIVITY: Experiment
TEACHING STRATEGY: Expository Guided Discovery
CONCEPTS: Heat causes air molecules to move apart Interaction Energy Transfer
SKILLS: Observation Inference
Objective: to observe the expansion of air when heated.
Materials: Balloons. Soda bottles.
Distribute the bottles and balloons to each student or group of students. Ask them what is in the “empty” bottle or in the balloon. Have them smell the air in each. Look at the inside of each to see that nothing is there except air. You can talk with them about the air that they can feel in the balloon when they close it, trapping air inside when they have discussed those characteristics of air and are quite certain there is nothing except air in either the balloon or the bottle, have them place the mouth of the balloon over the opening of the bottle.
If there is enough space near a sunny window, leave the bottles sitting in the sun until students notice change taking place. If it is winter when your heat source is on, you might place them near or over your hot air vent. when the students notice the balloons are expanding, dis¢ cuss the implication that holds for hot air ballooning. what might cause the balloon to expand? what happens when the bottle and balloon are put in a cool place?
Blow some soap bubbles or bring a burning candle flame near a hot radiator or other heat source. Let students observe the movement as the bubbles or flame are placed in different positions, When they note that the air above the heat source travels upward while the air near the floor moves downward, ask them to connect the “Growing a Balloon” activity to this and to hot air ballooning.