Rocks are Elastic!! Seeing is Believing

IRIS (Incorporated Research Institutions for Seismology)
Initial Publication Date: May 24, 2018 | Reviewed: March 6, 2019


This activity helps learners see the elastic properties of rocks by actually bending marble. How rocks respond to stress is a fundamental concept, critical to forming explanatory models in the geosciences (e.g., elastic rebound theory). Whereas learners are likely to have lots of experience with rocks, few will have directly experienced them behaving elastically. As a result of this "missed experience", most learners conceptualize rocks as rigid solids; a concept which generally serves students well in everyday life but impedes learning about particular geologic concepts.

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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 a demonstration or interactive.

Skills and concepts that students must have mastered

Learners should have some introduction to the idea that rocks store energy that is released during earthquakes.

How the activity is situated in the course

Generally it would make sense to have this fairly early in learning about earthquakes. It could also be done in conjunction with learning about the properties of solids in a physical science course.


Content/concepts goals for this activity

Learners will be able to:

  • Explain at least one way to demonstrate that solids, like rocks, can deform elastically.
  • Describe how the elasticity of rocks is fundamental to the earthquake cycle.

Higher order thinking skills goals for this activity

Not applicable

Other skills goals for this activity

Using physical models

Description and Teaching Materials

See attached file for educator notes, NGSS alignment, student exercise, and answer key.
ROCKS ARE ELASTIC!! Seeing is Believing Activity (Acrobat (PDF) 1.6MB Sep2 22)

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Teaching Notes and Tips

  • The rock tongs take some time to construct so read the directions and allow enough time.
  • Once constructed, the rock tongs do need to be treated with care. Learners should use them in a controlled environment. Students need to be coached on using them appropriately and not too roughly. With care they can last for years but if they are not treated well, they will show brittle failure by breaking.


The student worksheet serves as the summative assessment for the exercise. Alternatively, if rock tongs are being used for a demonstration or informal interactive activity, questions and discussions with learners can help the presenter gauge the level of understanding and help address misconceptions.

References and Resources