This unit begins with students experiencing, through text and video, a devastating natural event that caused major flooding in coastal towns of Japan. This event was the 2011 Great Sendai or Tōhoku earthquake and subsequent tsunami that caused major loss of life and property in Japan. Through this anchoring phenomenon, students think about ways to detect tsunamis, warn people, and reduce damage from the wave. As students design solutions to solve this problem, they begin to wonder about the natural hazard itself: what causes it, where it happens, and how it causes damage. 

The first part of the unit focuses on identifying where tsunamis occur, how they form, how they move across the ocean, and what happens as they approach shore. The second part of the unit transitions students to consider combinations of engineering design solutions and technologies to mitigate the effects of tsunamis. Finally, students apply their understanding to consider how to communicate about another natural hazard to stakeholders in a community.

*Note about recent changes to this unit - In February 2022 the development team adjusted the unit to include a new section building towards MS-PS4-3: Integrate qualitative scientific and technical information to support the claim that digitized signals are a more reliable way to encode and transmit information than analog signals. This updated version integrates a new Lesson 8 into the storyline that focuses on developing PS4-3 through further exploration of hazard communication systems and different signals used to send alerts to communities. Using text, images, and videos, students explore the evolution of emergency communication systems over time. They obtain information about the benefits and challenges of different systems, and in particular, the types of signals used to alert people. Students gather information from the text and multimedia to support the claim that digital signals are more reliable ways to transmit information. The remaining lessons in the unit are unchanged.