Extension Activity - The Geosphere

by David Robbins

This activity will integrate internet resources with the study of plate tectonics in our Science 7 Earth Science unit called “The Dynamic Earth”. This unit covers the basics of plate tectonics including: moving plates, types of plate boundaries, and the results on the landscape. We will take a close look at patterns of earthquake and volcano activity around the globe and attempt to make connections between past and present activities and continued tectonic movements. We will use the internet resources to find images and information on specific volcanoes around the world and to calculate the rate of motion of a particular plate boundary.
This extension activity will be in two parts. The first will be be a simple research component and will take advantage of the international nature of our students. Students will be asked to find and investigate a volcano that is closest to their home country and home city. They will use internet resources to find basic information and pictures of each volcano.
The second part will integrate math and plate tectonics. Using images from the internet, students will first calculate the average rate of motion of the ocean floor away from the mid Atlantic ridge. They will then determine the rate at which two cities on continents on each side of the ridge are moving away from each other.
The activity could be done in school - if enough computer stations have internet access, or as homework. In Kenya, it would be assigned as homework. Students could access the internet from their home or parent’s office connection.

Part I
Is there a volcano near your home? How close to where you live is the closest volcano? What type of volcano is it? Is it active? What causes volcanoes?

To answer these questions and more, go to bookmarks in the browser and find Images of Volcanoes (http://volcano.und.nodak.edu/vwdocs/volc_images/volc_images.html )

This gives you a list of volcanoes by region. Click on the region you are from. If your home is within a region enclosed in a yellow box - click on it. Click on a red triangle (a volcano) closest to your home.

Answer the Volcano questions below:

Location (in relation to your home) _____________________________

Latitude and Longitude _____________________________

Elevation (in feet and meters) ______________________________

Structure (caldera, shield, strato) ______________________________

Active or Extinct ______________________________

History of eruptions _______________________________

Cause of volcanic activity ______________________________

Other facts of interest ______________________________
Make sure to save two or three images of your volcano. To save an image, click on it and hold down clicker. Drag down to save image as and direct it into your folder.

Prepare to present your information to the class.

An interesting follow up activity would be to create a class web site entitled something like “Me and My Volcano”. Students would tell us something about themselves and where they live - relative to plate boundaries, earthquake and volcanic activity. (The International School of Kenya has students attending from over 50 different countries. They represent countries from Asia, Europe, Australia, Africa, Middle East, and North and South America. ) Depending on copyright, images from the Images of Volcanoes site could be used on their web pages. Students could access volcano and earth quake sites from time to time to check on current seismic activity and update their web page.

PART II.
How fast are tectonic plates moving? How can we determine this?

These questions will be answered by doing the following activity. Go to bookmarks and click Gif image 1364 x 900 pixels (ftp://ftp.ngdc.noaa.gov/MGG/images/WorldCrustalAge.gif ).

The image that appears is a color coded image of the Earth’s sea floor (The color legend is below the image). This image should be projected on a screen for the whole class to see. As the teacher scrolls around the map and reveals different parts of it, ask:

Can you see the continents?
What do you think the different colors represent?

The teacher will scroll to the area showing the ocean floor between North America and Africa. Students will be given maps of this region - with lines on it already prepared by the teacher. The lines represent the distinguishable colors of the ocean floor shown on the Gif image. These colors are:

- Dark blue light blue dark green yellow green yellow orange red

A thick black line runs down the middle of the map and represents the mid Atlantic ridge.

Students, referring to the projected image, will color in the segments of the ocean floor on their maps as represented by the image. When finished, they will have seven bands of color on each side of the mid Atlantic ridge. Each color represents rock on the ocean floor of a particular age. The teacher, when everyone is finished, scrolls down to the legend.

Fill in the chart below, writing in the age of the rock (in millions of years) for each color represented.

Color Dark blue light blue dark green yellow green yellow orange red

Age ____ ______ ______ _______ ____ ____ ___

The map given to students needs to have a distance scale on it. The scale needs to be figured out ahead of time and depends on the size of the map used.


Questions.

Where on the ocean floor between North America and Africa is the ocean floor the oldest?

Where is the ocean floor the youngest?

From what we have learned about plate tectonics, how do you explain the difference in age of the ocean floor? What specific processes must be occurring at the mid Atlantic ridge?

Students should now:

- draw a thin pencil line down the middle of each color segment from the mid Atlantic ridge to the coast of North America. We will work from one side of the ridge only.

- draw a straight line perpendicular to the ridge and rocks - connecting the tropic of cancer in Dakhla, Africa with Virginia Beach (above Cape Hatteras) in the US. This will be the line we use to measure distances.

Using the distance scale on the map, students now:

- measure the distance from the mid Atlantic ridge to the first pencil line they have drawn (start with red region of rock).

- write the distance from ridge to the red line below.

- continue and measure the distance from the ridge to each color line and enter the distances below. Remember - we will only measure the distance on the North American side of the ridge.

- write the distance (in km) from mid Atlantic ridge to each of the lines below.

- convert distance in km to distance in cm. and write that in the space provided.
(Hint - if 1 km = 1,000m, and 1 meter = 100 cm, then how many cm are in a km? Note: This is perhaps something better done on the board with the class.)

km cm km cm

Red line _____ ______ Dark green line _______ _______

Orange line ______ ______ Light Blue line _______ _______

Yellow line ______ ______ Dark blue line _______ _______

Yellow green line ______ ______


Now that we know how many centimeters each section of rock has moved (these number should be huge), now let’s figure out the speed that each section moved away from the ridge.

- Referring back to the table of age you filled in, divide the distance moved (in cm)
by each section by the age of each section (in millions of yrs).


Note: The teacher here may wish to go over with the students shortcuts for dealing with so many zeros. For instance, to divide 50,000,000 cm by 56,000,000 yrs, divide 50 million cm by 56 million yrs - the millions cancel (6 zeros) and we are left dividing 50 cm by 56 yrs. Another way is to set up the ratio 50,000,000/56,000,000 and to cancel out as many zeros as possible before attempting to divide. Either way would help -especially if you are allowing students to use their calculators - as only so many zeros can fit on standard student calculators.

Fill in the table below

Rates of motion (in cm/yr):

Red line _____ Dark green line _______

Orange line ______ Light Blue line _______

Yellow line ______ Dark blue line _______

Yellow green line ______


- Find the average rate of motion of the North American continent away from the mid-Atlantic ridge. (discuss in class how to go about this).

Answer _____________

Conclusions

Determine the rate at which North American and the African continent moved apart.

Imagine that you and a good friend (that you met while overseas) went to the beach every year. You go to Virginia beach, while your friend goes to a beach in Northwest Africa. How far apart are you? How much further apart would you be after ten years? Explain your answer in as much detail as you can.

Discussion of activity.

This activity is very appropriate and applicable to the science 7 classroom. We study plate tectonics, and perform a variety of activities in doing so. This activity takes the class one step further with the integration of the internet. The mathematics integrated into this activity is simple enough t be used at the grade 7 level. It is recommended that the teacher assist students in dealing with the large numbers involved.

I believe part one will make volcanoes more a part of their lives and everyday experiences. Rather that just study what they are and the types, this activity will help make them familiar with actual volcanoes around the world and where they are in relationship to them.
Part two allows them to use an actual color image and legend off the net to calculate and verify that plates do actually move - in this case away from each other. Using Africa as a reference should be of interest to them - as they are presently on this continent.

This project will work. It integrates well with a unit already covered. Students will have background knowledge of Plate Tectonics before doing this activity so it should serve to reinforce what they have learned. It has potential to be an interdisciplinary unit (see below). I will be sending this extension as well to ISK, hopefully for use by my sub this year.
The problem presently is with internet access. Luckily, most students have it from their homes or offices. Those that do not will use the library. The problem with this is with connection speed. Our servers are not “Up to speed” as far as connections go, and phone lines are not reliable. The alternative is to wack the sites and have the instant access to them in the classroom or computer room.

Teaching standards addressed.

As far as National Teaching Standards are concerned, many are the same as in the last extension I wrote.

1. Select science content and adapt and design curricula to meet the interests, knowledge, understanding, abilities, and experiences of students.

2. Teachers of science design and manage learning environments that provide students with the time, space, and resources needed for learning science. (includes)
- Make the available science tools, materials, media, and technological resources accessible to students.
- Identify and use resources outside the school.

3. Teachers of science engage in ongoing assessment of their teaching and of student learning. (includes)
- use student data, observations of teaching, and interactions with colleagues to reflect on and improve teaching practice.

Additional standards.

Content Standard D

As a result of their activities, all students should develop an understanding of
- structure of the earth system
- Earth’s history

This activity is integrated into an existing unit taught - The Dynamic Earth. It utilizes existing technologies and internet resources to help better develop student’s understanding of earth systems and seismic histories.

Program standards

The program of study in science should connect to other school subjects.
Use mathematics in all aspects of scientific inquiry.

Part I of this activity could easily be done in the Social Studies class, or as an interdisciplinary activity involving English, Social Studies, Math Science, and technology classes. It involves geography, elevation, history, mathematics, writing and oral reporting, and of course, the internet!

As was mentioned previously, the math used in this activity is at grade 7 level (with reinforcement from teacher). Its use will enable the students to have a better comprehension of a component of the Dynamic Earth - its moving plates.