Plate Tectonic - Volcanoes (2)
 Lab 

   
OBJECTIVES:
  • Exploring the products of a volcano.
  • Comparing the parts of a volcano to different types of models.
VOCABULARY:
  • ash
  • crater
  • lava
  • magma
  • vent
  • volcanic mud
MATERIALS:
  • lab sheet
  • toothpaste
  • vinegar
  • baking soda
  • flask (or graduated cylinder)
  • pan
  • model volcano
  • pictures of recent volcanoes (Internet)

Students create analogs for lava and magma.



BACKGROUND:

Volcanoes are a subject that fascinate young and not so young students alike. The power and the mystery of a volcanic event is truly an earthy phenomena. Students sometimes have a difficult time understanding that the shape of a volcano grows or builds up through time and it builds from the inside out. Eruption after eruption builds a mountain like structure,

The various styles of eruptions and magma compositions build different types of volcanoes. Young children have a difficult time understanding how an eruption occurs. In this lab, students are asked to look at analogs for a couple of eruptive styles that may be more familiar to them. In later grades, students will be exposed to other eruptive styles

Models can help students understand a subject if used correctly. However, most models are not to scale nor totally correct. In this exercise students will look at different "models" of a volcano and try to decide which parts are analogous to a real volcano.

PROCEDURE:
  1. Build a large volcano model prior to lab.
     
    MATERIALS: large flat wooden surface (2'x 2'), newspaper, Plaster of Paris(5-7 lbs.), old plastic bucket, spray paint, empty tuna can or jar with lid. If you wish to make a smaller model, reduce the amount of materials.
     
    STEP 1. Crumple up newspapers into balls, and tape them to the wooden surface in the shape and size of the volcano you plan to build, as drawn to the right.
      
    STEP 2. Mix about 5-7 lbs of Plaster of Paris in the bucket with enough water to form a pasty texture. Mold the Plaster of Paris over the crumpled paper into the shape of a volcano. Place the tuna can inside the top of the volcano. See figure to the left. Note - Plaster of Paris dries very quickly. You have approximately 15-25 minutes to work with it before it becomes hard.
      
    STEP 3. Allow the volcano to dry completely, then paint and create your own volcanic scenery.
      
  2. Show the students different pictures of volcanoes around the world. You may use the pictures provided or find pictures from the internet.The following sites may be helpful:

    http://www.meto.umd.edu/~jose/VOLCANOES/volcpage.html  
    This site has good pictures, including a simulated 3-D column of ash erupted out of a volcano.
     
    http://volcano.und.nodak.edu/vwdocs/current_volcs/current.html 
    Information on currently erupting volcanoes around the world, with links to each site

    http://vulcan.wr.usgs.gov/home.html 
    Excellent information on US volcanoes, as well as plate tectonics and geologic hazards.
      
    http://www.norvol.hi.is/   
    The volcanoes of Iceland and their eruption histories
     
  3. As you show the images, review the parts of volcano. A crater is the large area at the top; ash is pulverized volcanic rock which can either be in the air or a coating on the surrounding area, lava flows down the sides of the volcano; magma is molten rock while it is inside the volcano; and the vent is the actual opening by which the lava and ash come out.
        
  4. The vocabulary words reflect the different parts of a volcano and some of the volcanic materials that are erupted. However, note that not all volcanoes show all of these characteristics at one time. For example, in 1980 Mt. St. Helens ejected ash and volcanic mud, not lava. In contrast, the ongoing eruptions at Kilauea in Hawaii produce mainly lava.
      
  5. Set up the following items at each student station: a) a realistic model of a volcano; b) toothpaste; c) vinegar, baking soda, and a small flask in a pan. The realistic model should be made before hand using the instructions on the following page.
      
  6. Demonstrate an "eruption" to the students with the large model. Erupting the volcano requires that you place about 3 tablespoons of baking soda in the "crater". Pour about 1/4 cup of vinegar onto the baking soda in the "crater". The mixture will foam vigorously, and produce a strong smell.

    Another chemical that can be used for the eruption is ammonium dichromate. This compound must be ignited. It is more visual and a much better eruption analog, but some scientists feel it maybe carcinogenic. It can be purchased at a chemical supply house. The ammonium dichromate produces ash and fire, but also produces a mess!

    After you create the volcanic eruption, explain to the students that the explosion was a model of how some volcanoes erupt. Emphasize that volcanoes are not all the same. The following diagram can help show students how to compare the model with a real volcano.

MODEL
(ammonium 
dichromate)
MODEL
(vinegar+
baking soda)
MT. ST. HELENS HAWAII
emits gas emits gas emits gas emits gas
smells smells sulfur odor sulfur odor
sound fizz violent quiet
no fire no fire no fire red hot lava
ash no ash lots of ash little ash
cone shape no shape ash cone red hot lava
ash no ash lots of ash little ash
cone shape no shape ash cone lava cone
  1. Tell the students that they are going to make their own volcanic eruptions, using the materials at their stations. Instruct them to squeeze the tube of toothpaste to cause an "eruption". The toothpaste inside the tube represents magma, outside it is "lava". The students should only "erupt" the tube of toothpaste once.

    Next, have the students place a little baking soda in the flask, and then pour in an appropriate amount of vinegar. The mixture will foam vigorously, like an explosive eruption. Test this procedure in advance with your materials; this will determine the appropriate measurements for baking soda and vinegar to give to your students.
      

  2. After they have completed these experiments, have the students draw a line connecting the words magma, lava, ash, or mud to its appropriate part of the picture on their worksheets. On the 4th diagram, have the students draw a volcano with all of its components. Assist their drawing skills by putting the symbols to the right on the board.
      
  3. The important point to emphasize is that models are used to help understand how real volcanoes work. It will be difficult for the students to determine whether the right answer in some cases. The exercise should get students to think about and justify their answers

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