Friends School of Minnesota 8th graders have been studying states of matter. To learn about how gases behave they worked in groups to build tissue balloons of various sizes. They predicted which hot-air balloons would go higher: smaller/lighter balloons or bigger/heavier balloons. Then they went to the gym and filled  them with hot air to see if they were correct in their predictions.

8th-grade-balloons
Friends School of Minnesota science teacher Steve Moe works with 8th graders to fill one of their tissue balloons with hot air.

Classes of younger students came to watch such a cool science experiment. Science teachers Steve and Shane used a propane stove used to heat the air. Then the balloons were released to float up into the gym rafters.

8th graders observe the behaviors of different sized hot air balloons to learn about how the volume to surface area ratio affects how it behaves.
8th graders observe different sized hot air balloons to learn about how the volume to surface area ratio affects how they behave.

Students recorded the height and time aloft and recorded their findings. Many were surprised at the results. They had first thought that the smallest, lightest balloons would float the highest and stay up the longest. But it was just the opposite. The bigger the balloon, the better it went up. Why? Ask a Friends School of Minnesota 8th grader!