Seismic Slinky: Modeling P and S waves

IRIS (Incorporated Research Institutions for Seismology)

This activity was selected for the On the Cutting Edge Exemplary Teaching Collection

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This page first made public: May 24, 2018


Students will produce P and S waves using a Slinky© to understand how seismic waves transfer energy as they travel through solids. All types of waves transmit energy, including beach waves, sound, light, and more. When an earthquake occurs it generates four different types of seismic waves. We will focus on two of these: Compressional-P (longitudinal) and shearing-S (transverse) "body waves." These travel through the Earth with distinct particle motion and predictable speed.



This activity could be done with most any novice geoscience learning group from late elementary through secondary or even early college. It can also work for informal education or public outreach venues as an interactive demonstration.

Skills and concepts that students must have mastered

It is best if the learners have some knowledge of earthquakes and earthquake waves. This activity goes well after the interactive demonstration Human Waves.

How the activity is situated in the course

This should probably come after a general introduction to plate tectonics but can be fairly early in learning about earthquakes.
It could also be done as part of a physical science unit as an applied example of wave types and characteristics.


Content/concepts goals for this activity

By the end of the exercise, learners should be able to:
  • produce both P and S waves using a Slinky©
  • use the model as a tool to observe and understand waves properties
  • describe wave components and volcabulary (period/wave length, amplitude, crest, trough, etc.)

Higher order thinking skills goals for this activity

Compare and contrast the difference between P and S seismic waves based on the direction of particle motion relative to the direction of propagation.

Other skills goals for this activity

Using and explaining physical models of natural processes.

Description and Teaching Materials

See attached file for educator notes, NGSS alignment, student exercise, and answer key.
Seismic Slinky Activity (Acrobat (PDF) 2.4MB May17 18)

Teaching Notes and Tips

  • You will need to caution students to treat the Slinkies with care as they can tangle and get bent.
  • It is great if you can invest in at least one "Super" Slinky for large group demonstrations. These are 8" when compressed rather than the 2.5" of the "Original" Slinky. Treat the Super Slinky with care, however, as they are particularly prone to tangling. Super Slinky needs to be stored on a rod or stand.


The student exercise serves as the summative assessment for the activity. Most questions have clearly correct answers. Alternatively, if the activity is being used for a demonstration or informal interactive activity, questions and discussions with learners can help the presenter gauge the level of understanding and to address misconceptions.

References and Resources