In this Data Puzzle, students compare the amount of heat given off by a hydrothermal vent with the amount of heat needed to bring a kettle of water up to boiling temperature. Recognizing that the heat released from one vent in an hour would heat a cup of coffee/tea/cocoa for every man, woman, and child in a
good-size town helps students to realize the large amount of heat that comes from the interior of the Earth.
This puzzle works well in an Earth science or elective geology class or in an undergraduate marine geology class.