Rocks Demonstrations

See also: Soil and Erosion, Mining and Resources, Plate Tectonics

Rock demonstrations examine how rocks form, change, and reveal Earth’s history. These activities help students connect the visible features of rocks to the processes that created them.

Demonstration	Materials	Difficulty	Safety	Summary
Wind Erosion	★☆☆	★☆☆	★☆☆	This activity demonstrates how wind erosion moves sediments and how variables such as soil moisture, particle size, and protective coverings affect the rate and extent of erosion. A hair dryer simulates wind blowing across different soil conditions.
Testing Rock Hardness	★★☆	★☆☆	★☆☆	Students perform a scratch test to compare the hardness of different rocks. They discover that harder rocks can scratch softer ones and explore how rock hardness affects their practical uses.
Sedimentary Rock Snacks	★☆☆	★☆☆	★☆☆	Using rice krispies, marshmallows, chocolate chips, and candies, students create layered snack bars that model the formation of sedimentary rocks in the rock cycle.
Seafloor Spreading Model	★☆☆	★☆☆	★☆☆	Students build a paper model to demonstrate how new ocean crust forms at mid-ocean ridges through seafloor spreading and is consumed at ocean trenches, helping visualize the cycle of crust creation and destruction.
Rock Testing and Classification	★★☆	★☆☆	★☆☆	Students test rock samples for properties such as hardness, luster, texture, porosity, and reactivity. They record observations, classify each sample as igneous, sedimentary, or metamorphic, and connect their findings to real-world engineering challenges.
Pangaea Puzzle	★☆☆	★☆☆	★☆☆	In this activity, students use fossil evidence, rock strata, and continental shapes to reconstruct how Earth’s continents were once joined together as the supercontinent Pangaea about 220 million years ago. By piecing together cutouts of landmasses, they explore the evidence supporting plate tectonics.
Making Light by Rubbing Quartz	★★★	★☆☆	★☆☆	In a dark room, rub or strike two pieces of clear quartz together to produce brief flashes of light and a faint odor. This visible glow is triboluminescence - light emitted when crystals are stressed, fractured, or rubbed.
Making Fossils	★★☆	★☆☆	★☆☆	Students create fossil replicas by pressing shells, leaves, or other objects into plasticine to form a mold, then filling it with plaster of paris. The plaster hardens into a fossil-like cast that can be painted for detail.
Lava Flow Races	★☆☆	★☆☆	★☆☆	Students simulate volcanic lava flows using golden syrup to represent liquid lava. By adding sprinkles (crystals) and marshmallows (rock fragments), they investigate how cooling and crystal formation increase lava’s viscosity and slow its movement.
Grow Egg Geodes	★★☆	★★☆	★★☆	Empty and clean eggshell halves are coated with glue and alum powder, then soaked in a hot, colored alum solution so clear alum crystals grow inside the shells, forming geode-like ornaments within a day.
Geological Timeline with Toilet Paper	★☆☆	★☆☆	★☆☆	Using 46 sheets of toilet paper to represent Earth’s 4.6 billion-year history, students create a scale model timeline where each sheet equals 100 million years. Timeline markers show that most major biological and geological events occur only in the last few sheets.
Gelatin Volcano Model	★☆☆	★★☆	★☆☆	A cup of gelatin represents country rock while pudding, yogurt, or sauce injected into it simulates magma. As the “magma” intrudes and erupts, the activity models subsurface magmatism, intrusive rock formations, and surface volcanism.
Freeze Thaw Weathering	★★☆	★☆☆	★★☆	This demonstration models freeze–thaw (ice wedging) weathering using water-saturated chalk or sandstone that is repeatedly frozen and warmed. Expansion of freezing water inside the porous chalk weakens it until it cracks and breaks, simulating how rocks fracture in nature.
Crayons Rock Cycle	★☆☆	★☆☆	★★☆	Students use crayon shavings to model the rock cycle by forming sedimentary, metamorphic, and igneous rocks. Heat, pressure, and cooling are simulated to show how rocks change form over time.
Cracking Apart	★★☆	★★☆	★★☆	Granite chips are heated in a Bunsen flame until glowing and then rapidly cooled in cold water, simulating the physical weathering of rocks caused by extreme temperature changes in desert environments.
Chemical Weathering	★★☆	★☆☆	★☆☆	This demonstration shows how acid can chemically weather sedimentary rocks. Vinegar simulates acid rain reacting with chalk or limestone, representing how minerals in rocks break down and form new materials.
Baking Soda and Vinegar Volcano	★☆☆	★☆☆	★☆☆	A cone-shaped volcano model is built around a bottle. A mixture of bicarbonate of soda, water, and washing-up liquid is placed inside, and vinegar with food coloring is added to create a foamy eruption that resembles lava flow.

Materials
★☆☆ Easy to get from supermarket or hardware store
★★☆ Available in most school laboratories or specialist stores
★★★ Requires materials not commonly found in school laboratories

Difficulty
★☆☆ Can be easily done by most teenagers
★★☆ Available in most school laboratories or specialist stores
★★★ Requires a more experienced teacher

Safety
★☆☆ Minimal safety procedures required
★★☆ Some safety precautions required to perform safely
★★★ Only to be attempted with adequate safety procedures and trained staff