Candy Bar Plate Tectonics

A layered candy bar models Earth’s brittle crust over a softer mantle. By cracking the chocolate surface and applying compression, tension, and shearing, students observe faulting and plate-boundary behaviors.

1. Gather materials: layered candy bar (chocolate over caramel or nougat), paper towel or plate, clean hands or disposable gloves, toothpick for pointing, and a notebook.
2. Make small cracks in the chocolate surface with a fingernail or toothpick tip to create fault lines. Place the bar on the paper towel.
3. Compare candy layers to Earth’s layers. Typical mapping: chocolate crust = lithosphere, sticky layer = upper mantle (asthenosphere), lower filling = lower mantle. Note the missing layer is the core.
4. Record definitions: cracks are faults; large rigid pieces are tectonic plates.
5. Compression test: press the ends of the bar gently toward each other. Observe blocks overriding or arching upward, and record.
6. Tension test: pull the ends of the bar gently apart. Observe gaps opening and blocks dropping into the soft layer, and record.
7. Shearing test: hold the bar with both hands and push one end forward while pulling the other back. Observe side-by-side sliding along faults, and record.
8. For each force, link what you saw to a plate boundary type and a fault type in your notes.

Candy Bar Plate Tectonics - HrinzScienceClass:

📄 Candy Bar Tectonics - Science Spot: https://sciencespot.net/Media/candybartectonics.pdf

• Warm the bar slightly in your hands versus chill it first to compare brittle versus ductile behavior.
• Try different bars (with nuts, wafers, thicker caramel) to see how composition affects fault styles.
• Sprinkle a dusting of cocoa or powdered sugar on top before cracking to highlight displacement along faults.
• Cut the bar into two or three “plates” and slide one beneath another to model subduction at convergent boundaries.

• Check for food allergies and ingredient warnings before handling or eating.
• Wash hands before and after the activity; do not eat if any lab chemicals or nonfood surfaces contacted the candy.

• What do we call the cracks in Earth’s surface? (Faults)
• What do we call the large pieces of Earth’s crust? (Plates)
• Which Earth layer is missing from the candy model? (Core)
• Compression: what did you observe, and which boundary and fault does it model? (Blocks push together or override; convergent boundary; reverse or thrust fault)
• Tension: what did you observe, and which boundary and fault does it model? (Blocks spread apart and some drop into the soft layer; divergent boundary; normal fault)
• Shearing: what did you observe, and which boundary and fault does it model? (Blocks slide past each other; transform boundary; strike-slip fault)
• Where else do you see compression, tension, and shearing in real life? (Examples may include compression in building supports, tension in stretched materials or rift zones, shearing from wind loads on tall structures)