Objective

Students will learn about buoyancy.

Class Arrangement

Arrange the class into small cooperative group.  A good size is four.  One member of the group should be assigned the role of foreman or leader, and be responsible for coordinating the group’s effort.  The next member should be responsible for gathering and care of equipment.  The third member is the recorder who will write, record, and keep all written material organized.  Another member is the reporter, who is responsible for giving the oral report and presentation.

Materials

Per group of three or four students:
Helium balloon, paper clips, bucket of water, and small plastic bag

Procedure

1. Gather materials for experiments.
2. Hold helium balloon and watch as it floats in the air.
3. Now try to make the balloon balance in the air so it is not floating or sinking.  Do this by adding paper clips on the string of the balloon.
4. Add and subtract paper clips until the balloon balances.
5. Record results on lab report sheet (one per group).
6. Place plastic page with air in the water.
7. Now try to make the plastic bag balance in the water so it is not floating or sinking.  Do this by adding paper clips in the bag with air.
8. Add and subtract paper clips until the bag is submerged but not sinking.
9. Record results on lab report sheet (one per group).
10. Report findings to the class.

Students will report their findings to the class.
Students will complete two lab report sheets per group.

Conclusion

Teacher will explain that air and water react in the same way.  Like water, air can hold up the air above it.  That is why hot air balloons float in the air.   It’s not the propane that holds the balloon up, it’s air.  Now you know why objects float when they are submerged in a fluid, such as air or water, that can support them.