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Bob Henry Reading Seismic Signals Program Title: Volcano's Deadly Warning Subject(s): Earth Science Grade Level: 9th grade

Bob Henry helps his students understand the differences between four seismic wave patterns so they can draw representations of what they are seeing.

"Is the Yellowstone hot spot going to erupt? Will we have any warning? What will happen to us?"

Bob Henry usually hears these questions as his environmental geology class winds up its study of volcanoes. This year, with the help of the NOVA program "Volcano's Deadly Warning" and companion Web site, Henry provided students a window into one scientist's hypothesis about predicting volcanic activity.

Henry, who has been teaching for 24 years, always tries to find a way to make local connections for the Earth Science concepts his 9th-grade students study at Jackson Hole High School in Jackson Hole, Wyoming. The variety of landforms in Wyoming provide a natural springboard for these connections.

This year, when students asked questions about the Yellowstone Hot Spots, Henry had them explore Seismic Signals, an online activity that demonstrates the differences between the various types of earthquakes that originate within volcanoes. In the lesson, students observe and draw sketches of four seismic wave patterns. The activity helps students learn that volcanoes that are becoming active exhibit different wave patterns than those that are dormant.

The activity also helps students better understand the work of Bernard Chouet, the scientist featured in the NOVA program who is developing a new hypothesis for predicting volcanic eruptions.

After they completed the online activity, Henry had students view the first half of "Volcano's Deadly Warning" and discuss why someone would want to live near a volcano and what the tradeoffs are between the rich soil and the potential danger. After viewing the second half of the program, students discuss whether Chouet has a scientific theory or a working hypothesis for predicting seismic activity. Henry says this NOVA program was particularly useful in helping students to understand and become more familiar with the difference between these two concepts. Through a guided discussion, the class concludes that Chouet has developed a hypothesis that he can refine as he continues to gather more data. Eventually his hypothesis can become a piece of a larger theory that incorporates all of the scientific understanding of volcanism.

Finally, students explore the Sine Wave Science classroom activity that investigates constructive and destructive interference of sine waves. Henry says this activity helps students recognize that once you identify simple wave patterns, you can add them together to make complex wave patterns. Students then recognize that complex seismic waves can be broken down into combinations of simpler waves. Patterns of these simpler waves can be used to better understand the status of a volcano.

Henry modified this activity in several ways so that students of all math levels would be successful. For example when adding the waves together, Henry had students who needed additional math support use a ruler to look at one location along the two waves at a time. He worked closely with these students to help them add the two locations together and then graph the new point as part of complex wave patterns. Henry had students with more advanced math backgrounds identify when the complex wave pattern starts to repeat.

Henry said this lesson segues into a unit on earthquakes. Between this activity and one they complete during the earthquakes unit, Henry says students begin to think of seismic waves as analytic tools. "Waves become more than just squiggles on a paper in science class," Henry says. "Students begin to realize waves help us to better understand, analyze, and predict phenomena in this ever-changing world in which we live."

For more information, Henry can be contacted at