Elizabeth Davis-Volcanic Landforms
Principles investigated:
- This activity lends itself very well to 6th grade earth science, during which students investigate Earth's changing surface. An ideal time to implement this lesson would be when discussing tectonic plates and the geologic features that form as a result of plate movement.
- It is also a great opportunity to view and map local and/or regional volcanic landforms and activity, or to correlate volcanic activity with the occurrence of earthquakes and how both relate to plate boundaries.
Standards:
1. Plate tectonics accounts for important features of Earth's surface and major geological events. As a basis for understanding this concept:
b. Students know Earth is composed of several layers: a cold, brittle lithosphere; a hot, convecting mantle; and a dense metallic core.
f. Students know how to explain major features of California geology (including mountains, faults, volcanoes) in terms of plate tectonics.
Materials (per group):
1 cookie sheet
1 1 oz bottle of sodium tetraborate (note: you can make your own out of borax, but I don't recommend it--it doesn't have the same effect)
1 1 oz bottle of polyvinyl alcohol
1 vial (or small scoop) of dehydrated gel (potassium polyacrilate)
1 pipette or eye dropper
2 small plastic cups or beakers (clear is good--the kids like seeing the materials through the container)
1 craft stick
3 books (or something to lean your cookie sheet on--ultimately creating an incline)
1 metric ruler
timer/stopwatch/wall clock
Procedure:
1. Put on your safety gear (goggles). For kids who may have sensitive skin, gloves might be good. Although, I've never run into a problem.
2.It's important to have a procedure in place for materials. It's not practical for teachers to be passing materials out all period long, so it's good to utilize "materials managers". This year I incorporated two materials managers into my weekly jobs. I list the jobs on the whiteboard by the door, and each week it rotates. It is intertwined with my behavior system, so the kids run it and it has worked like a charm. Our rule is that as tables receive materials they go in the center of the table, hands-off, until directions have been given and they have received the thumbs up from me.
3. Empty the entire bottle of polyvinyl alcohol into one of your clear cups (have students note how it feels to the touch--long, sticky polymers that are slippery to the touch.
4. Using an eyedropper or pipette, add 1 mL of the sodium tetraborate to the same cup with the polyvinyl alcohol. Then, add a second 1 mL pipette. NOTE: remind students they will want to add only a few drops at a time (if using an eyedropper), or 1mL at a time (using a pipette) because if they add too much, their "mafic lava" is ruined :(
5. Using your craft stick, stir up the combination. Students will enjoy observing how the two create a sticky "slime". This is representative of the low silica (mafic) lava that emerges from shield volcanoes, producing lava flows, and a generally "quiet", or effusive eruption.
6. Ask students to experiment with the ooze on a hard surface (like a tabletop or desk). They can tip the cup over and observe what happens to the ooze. Encourage them to imagine that this is how iron rich volcanic glass moves once it escapes from the vent of a volcano
7. Add a capful of dehydrated gel (potassium polyacrilate) to the second portion cup. Fill the portion cup two thirds full of water and observe as the material absorbs all of the water (and then some). This represents high-silica (felsic) lava that is emitted from cinder cone volcanoes (producing an explosive eruption).
8. Prepare your data table. (see below for example)
9. After preparing an incline (use your cookie sheet and prop it up on a few books), place your (for lack of a better term, "blob") of felsic (high-silica) lava at the top of the incline. Students will observe that it doesn't really move (slow moving) and kind of "sits in one spot". Felsic lavas are extremely viscous, and typically fragment as they extrude. Ask them to observe how this is similar to how cinder cone or composite volcanoes form/look.
10. Have students poor their ooze (mafic lava) next to their blob (felsic lava) and observe the variations in how each moves.
11. Have students track the distance each travels and graph their data.
Prior Knowledge: It would be good for students to have a working knowledge of the composition of Earth's three layers. As well, a basic understanding of plate tectonics and the way that plates interact at their boundaries will help them make connections during this lesson.
Explanation: Not all lavas are created the same! Volcanic lava can produce large, flat, deposits, called lava plateaus, as well as mountains that reach thousands of feet into the sky. Through this activity students are able to gain a visual, more concrete understanding of how that occurs.
Pictures: (will also try to post more following the demonstration)
Questions:
Q1: What determines how fast lava flows?
A1: The silica content determines not only the viscosity, but also how quickly lava will flow.
Q2: How do volcanic eruptions help scientists learn about Earth's interior?
A2: The deepest samples of the Earth’s interior brought up from drill holes come from a depth of approximately 12 km. Volcanoes provide direct samples of the Earth’s interior from much greater depths, at least 100 km, and, perhaps, as deep as the core-mantle boundary.
Q3: How does plate tectonics relate to volcanic activity?
A3: Volcanoes generally form at plate boundaries, where two plates are colliding. One plate goes under the other (or subducts. This is known as a subduction zone. Interestingly, if one researches active volcanoes, he/she will probably observe that
Where can I buy supplies?
A good site to purchase these specific Note: attached are a couple of worksheets that you can tweak to make your own. I use the lava races sheet and have my students do a "write up" in their science notebooks. It's a good activity to incorporate both graphs and use of technology. Lots of extensions!
References:
*This original idea came from a conference I went to presented by "Loose in the Lab". I have since taken the idea and tweaked it to fit my classroom. Note: the worksheets "lava races" and "volcanic landforms" that are attached are from the loose in the lab books. Loose in the Lab offers cool grade-level conferences that are focused on hands-on activities for the CA content standards. If you're interested in checking out a conference you can learn more at www.looseinthelab.com.
Other ideas:
Caldera Box; A Place in Time; Volcano World Lesson Ideas; Snack Tectonics (see attachment)