## Inflation and Horizontal Extension (Grades K-3)

Balloons are excellent tools to demonstrate the relationship between
inflation and changes in horizontal distance. Balloons, markers, rulers,
and a simple map of Kilauea Caldera are needed. Students can work in
pairs or small groups. Inflate a balloon three-quarters full. Outline a
simple map of Kilauea caldera on the top of the balloon. Label three
points on the outside rim of the caldera. Measure and record the
distance from each point to the other two points. Inflate the balloon
as large as possible. Remeasure the distance between the points. The
distance between all the points increases. Compare the balloon to
Kilauea Volcano. As the volume of magma in the reservoir increases, the
volcano inflates, and the distances between points on or near the rim of
the caldera increases.