======Earthquake Shake Table======


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**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
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**Categories:** {{$demo.categories}}
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**Alternative titles:** Marshmallow Earthquake Engineering
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====Summary====                   
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====Procedure====  
  -Prepare the “shake table” by setting Jell-O in shallow baking pans the day before; keep covered so it stays springy.
  -Explain the design challenge and constraints: structures must be ≥2 toothpick levels high and include at least one triangle and one square.
  -Have students sketch ideas (label triangles, squares, footprint size, height) and then build prototypes using 30 toothpicks and 30 mini marshmallows.
  -Demonstrate a standard test: mark the table so every pan is shaken the same distance and for the same time using a steady back-and-forth shear motion.
  -Test one model at a time on the Jell-O; observe stability, tilting, and failures. Make a quick “after” sketch.
  -Discuss what worked (for example, cross-bracing, lower center of mass, wide base) and what failed (for example, tall slender towers without bracing).
  -Redesign and rebuild a second prototype that addresses weaknesses (add X-bracing, widen base, taper upper stories, tie levels together).
  -Retest using the same shaking protocol; compare first vs. second results and record conclusions.



====Links==== 
Earthquake in the Classroom - TeachEngineering: 
{{youtube>mMnEXukSmdg?}}\\

📄 Testing Model Structures: Jell-O Earthquake in the Classroom - ncwit.org
 - AUTHOR: [[https://www.teachengineering.org/activities/view/cub_natdis_lesson03_activity1]]\\

📄 Earthquake IN THE CLASSROOM - Cairns Regional Council: [[https://www.cairns.qld.gov.au/__data/assets/pdf_file/0011/469271/Earthquake-in-the-classroom-experiment.pdf]]\\

====Variations====
  *Add “base isolation” by placing the structure on a stiff card resting on a few marbles/coins to model sliding supports.
  *Change one variable at a time: height, footprint size, amount/location of bracing, or number of stories.
  *Investigate “soft story” effects by making the first level taller/less braced and comparing performance.
  *Explore resonance by shaking at different speeds and noting which frequency most strongly excites the structure.



====Safety Precautions====
  *Do not eat the marshmallows or Jell-O used for testing; keep food items separate if offering a snack later.
  *Wash hands before and after building; clean surfaces that contact Jell-O.
  *Keep spills wiped up to avoid slips; cover pans when not in use to prevent drying and contamination.
  *Use toothpicks carefully to avoid punctures; dispose of broken toothpicks promptly.




====Questions to Consider====
  *Which design features helped most? (Cross-bracing/triangles, wide “footprint,” tied-together levels, and lower center of mass.)
  *Why do triangles help? (They prevent shape distortion by resisting shear, adding lateral stiffness.)
  *How does Jell-O represent real ground? (It models flexible, moving soil layers that transmit seismic waves.)
  *How did you keep the test fair? (Same shaking distance, speed, and duration for every trial.)
  *Why might a tall, narrow model fail more easily? (Higher center of mass and greater bending moments increase overturning and sway.)
  *What does base isolation change? (It reduces motion transmitted into the building by allowing controlled sliding under the structure.)