Plate Tectonic - Volcanoes (1)

  • Experimenting with different types of "lavas"
  • Exploring how liquids flow.
  • Hawaii
  • Kilauea
  • lava
  • liquid
  • viscous
  • volcano
  • vegetable oil
  • water with red food coloring in it
  • sand
  • liquids of 2 different viscosities, such as 40 weight motor oil, Karo Syrup, honey, syrup, or ketchup
  • water with blue coloring in it
  • Video tape of volcanoes or any other short clip that shows flowing lava

Students experiment with different liquids to simulate lava.


Vulcanologist sampling hot magma in Hawaii.


Rock is the solid state of matter, while lava (outside the Earth) or magma (inside the Earth) is the liquid state of matter. Cooling of the lava will change the state of matter to solid.

Students at this grade are familiar with water, honey, vinegar, and syrup, but not molten rock. Molten rock is a liquid. The thickness of a fluid is called its viscosity. Viscosity is technically defined as the amount of internal resistance to flow in a liquid, which depends of how "sticky" the molecules and atoms in the fluid are. Water, a fluid we are all used to has relatively low viscosity. Molten rock has a high viscosity; it is much thicker, more like wet concrete or cold honey. Lava (molten rock that flows on the surface of the Earth), actually has many different viscosities, which are largely controlled by the temperature of the lava and its composition.

Students are familiar with how water flows, but they sometimes don't realize that other substances like oil or sand can also flow. This activity familiarizes the students with the concept of viscosity. The class should first watch parts of a video which show real viscous lava flows.


  1. Set up 5 stations. At each station have 2 cups and a different material: red water, blue water, oil, syrup, or sand. In the lab, the students will pour the contents of one cup into another. You may want to put trays, buckets, wax paper, or newspaper under the experiment in case a spill occurs.
  2. Show the class portions of the Kilauea video tape that illustrate flowing lava. A good section to use is the point at which the lava flow engulfs the schoolhouse. Emphasize the movement of the lava and point out the different speeds of the lava flow. Describe the movement of the lava as "viscous flow". Although this is an unfamiliar word for the students, it correctly labels the lava flow as having a slower rate of flow than water.
  3. Divide the class into groups. Have the groups move from station to station. They should pour the liquid at each back and forth, mentally noting its viscosity. When they have completed all 5 stations, have them return to their seats and discuss which liquid most closely resembled the lava seen in the video and why. Remind them not to think of color, but how the liquid moves (how viscous a substance is).
  4. Take a poll of the students to see which liquid they observed to be most similar to the lava flow. They might choose the water with red food coloring because of the red color. Try to illustrate that the motor oil or syrup is more viscous, and therefore similar to the lava. The point is not to convince the students of the right answer, but to get them thinking.

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