Paper (preferably white) at 3-4 feet in length and 2-3 feet across
Small toy cars, people, or houses (for scale)
Marker or chalk for drawing on the board
Large bucket of water
Topsoil (or any black or earthy dirt)
Aluminum or plastic container to hold dirt and sand
Red food coloring
Empty 20 oz. plastic bottle
Available from the geoscience education department at Michigan Tech:
Lava samples from Hawai'i and Washington
Local pieces of igneous rock
Ash from Mt. St. Helens
Posters of volcanoes, debris flows, ash, etc.
Seismogram of Mt. St. Helens
Ask students to identify the 3 types of volcanoes: shield, cinder cone, and composite. Ask students to describe each and where they might be found. (Younger students may have no idea. Ask leading questions and work with them. It could turn out to be a good geography lesson.)
Shield volcano: forms in island arcs. A good example is the Hawai'ian chain. A very large broad-shaped volcano. Draw a picture. Show a poster of a shield volcano. Pull out the dirt. Have one of the kids mix the dirt with water to form a thick mud. Then have the kids slowly pur the mud into the container. Repeat until a small wide mound forms. Explain that this is how shield volcanoes develop--with slow-moving lava piling up like the mud.
Cinder cone: forms in subduction zones where silica-rich rocks exist. If the kids are old enough, you could talk about plate tectonics. These are very explosive, sharp, steep volcanoes and are often the most dangerous. Draw a picture and point to a poster example. The story of Pompeii might be worth telling. Have one of the children grav a handful of sand. Let the child pour the sand in one spot. Notice that a peak will develop and the sides will be relatively steep. Cinder cones send material up into the air and some of it comes back to the starting point. This sand cone resembles a cinder cone.
Composite cone: a hybrid of the two types. Draw a picture and show a poster. Have a couple of the kids alternate pouring mud and sand over a point to show how a composite cone forms.
What does lava look like?
Ask the children what lava looks like (color, texture, etc.). Take a piece of pahoehoe lava. Have the students repeat the name. Tell them it means "smooth and ropey" in Hawai'ian. Let the kids run their hands over the piece. Pull out a piece of aa. Tell them it means "sharp and jagged." Pass it around. Explain that these lava types (especially pahoehoe) are found in shield volcanoes. Show off the other lava types, what they look like and where they are from. Pass around ash from Mt. St. Helens.
Do rocks float?
Ask the kids if rocks float. Pull out the bucket of water, a piece of pahoehoe, and a piece of pumice. Have the first child drop the pahoehoe into the water. It will sink. Now have the second child repeat the experiment with the pumice. It will float. Ask the kids why...
Mud vs. lava: the race
Ask the kids why geologists study volcanoes (inevitably they will say because they are dangerous or the lava is dangerous). Choose two students. One will have a cup of lava (Karo syrup); the other will have a cup of mud. Place the paper taped to the wall about 3 ft. off the ground at the top and one foot away from the wall at the bottom taped to the floor. This will be the side of your mountain. Spread newspapers across the floor to catch the mud and the syrup. Place the toy cars at the base. Ask the class which is faster: the mud or the lava. Then at the count of three, have both students dump the mud and the lava onto the paper (mountainside). The mud should engulf the cars very quickly. Explain that mudslides are often more dangerous to people than lava. Show some pictures of mudslides.
To finish off the demonstration with a bang, make your own volcano. There are many different ways of doing this, but perhaps the easies is to simply take a 20 oz. empty plastic soda pop bottle and fill it 1/4 of the way full with baking soda. Take a cork from a wine bottle and wrap tape around it until it fits the bottle snugly. Remove the cork and keep it by your side ready to plug the bottle. Add a few drops of red food coloring to the vinegar. Dump the vinegar solution into the bottle and plug it, making sure that the top is pointed away from everyone. When the pressure builds up, the cork will fly and lava will be sent everywhere and will pour down the sides!
Wear old clothes.
Make sure everyone is far enough back to not get sprayed with the homemade volcano.
Use goggles or wear safety glasses when you cork the volcano.
Shawn Len, 2000.