Introduction and Making Clay Models
- Tell students that when we study watersheds it is useful to know how the land dips and rises – where the hills, valleys, ridges, stream beds, and plains are. Most maps don’t tell us this information. They may show cities, roads, and rivers, but not valleys, ridges, and mountains. Tell students that there is a special type of map called a topographic map that does show how the land rises and falls.
- Give students copies of various topo maps. Ask them what they notice. Have them trace a contour line and tell them what a contour line is. Have them notice how some lines are labeled with the elevation. Have them look for hills by finding concentric circles. Have them look for steep places by finding lots of lines close together and look for flat places by finding lines spaced very far apart. If you have a raised relief map available, help students draw comparisons between the two and see a relationship between these two types of maps. Their understanding will be, and should be, very superficial at this point.
- Tell students that over the next few days they will be making a model clay island, making a topo map of their island, giving their topo map to another group, and that other group will try to recreate their island using clay or other materials. Divide students into groups.
- Give each student their first set of materials for making clay models and give them rules for their islands:
- islands should fit on their transparency
- islands should have high and low regions such as mountains and valleys
- islands should not have extremely steep cliffs or overhangs
- islands should not be too complicated
- on the highest point of the island, place an “x” using the other color of clay
- Give students 15-20 minutes to make their islands. Circulate among them making sure they are following the rules. Groups that finish early can add features such as a peninsula near the water, a stream coming down the mountainside, etc.
Making a Topo Map of the Model
- Using one of your students’ clay models, demonstrate the procedure for making the topo map.
- Use the marker to label North, South, East and West on the transparency below the clay model.
- Label the compass points on the large sheet of transparency as well.
- Place the clay model in the bottom of the plastic container.
- Place the lid over the container with the transparency on top, oriented the same way (according to the compass points) as the clay model below.
- Holding your head very still above the lid, trace the shoreline of the island onto the transparency using the marker. Also trace the cross at the top of the tallest hill. This cross will be a reference point to help figure out where to put your head.
- Remove the lid. Holding a ruler inside the container near the base of the island, pour blue water into the container until the water is 1 cm deep. Notice how the water creates an imaginary line where the elevation above “sea level” is 1 cm all the way around.
- Replace the lid and the transparency, making sure the transparency is oriented correctly. Match the first coastline and the cross to the island below.
- Again, holding your head very still, trace the new shoreline of the island – where the water level touches the model. (You can probably end the demonstration here. Students should continue onto the next step.)
- Repeat adding water and tracing new contour lines until the island is completely submerged.
- Give students the second set of materials. My students needed 30-45 minutes to create their maps.
- When all the students are finished, you can assess their understanding so far by placing all the models up at the front of the room and collecting all the maps. Place a map on the overhead projector and look at its features. See if students can tell which model it belongs to. Use features such as the number of hills, distinctive coastlines, valleys, etc. to help students identify which model goes with which map.
Making Models from a Topo Map
- Make a photocopy of each map. The original map should be left as untouched as possible while the photocopy is a working copy that may be cut up if necessary.
- Using one of the students’ topo maps, demonstrate how to make a model from a topo map. See the table below:
|Salad Tray Tops
|1. Trim the photocopy of the map so that it just fits on the flat bottom of a tray.
2. Trace the outermost contour line onto the first tray.
3. Trace the next contour line onto a second tray and stack it on top of the first.
4. Continue tracing and stacking until all contour lines have been traced.
| 1. Make a bunch of balls of clay approximately 1 cm tall.
2. On the photocopy of the map, write an “N” on the inside of each contour line on the North side of the island.
3. Hold the photocopy tightly on top of a piece of cardstock. Cut both the photocopy and the cardstock together along the outermost contour line. Label the north side of the cardstock with an N. Set this piece aside.
4. Hold the now smaller photocopy onto a new section of the cardstock and cut out the next contour line and label the north side. Stack this new piece of cardstock on top of the first using some clay balls as spacers to raise it up off the first.
5. Continue cutting out pieces of cardstock and stacking them until all contour lines have been cut out.
Give each group the original and photocopy of a different group’s topo map as well as the other materials. If you want, have students use the maps to predict what the model will look like before they actually make the model. Allow students 30-45 minutes to create their models.Once all the models have been completed, put the original model, the map, and the second model side by side. Were there any problems? How similar are the two models? How are they different? Why aren’t they exactly the same? Look at the models to discover how different features (hills, valleys, ridges, plateaus, etc.) appear on the maps.If you have time, go back to the example topo maps that were shown at the very beginning of this lesson. See whether students are able to identify elevations, features, and identify trends on the maps now.
Submitted by irene on Mon, 2005-11-28 18:58
| 1. On the photocopy of the map, write an “N” on the inside of each contour line on the North side of the island.
2. Hold the photocopy tightly on top of a piece of foam. Cut both the photocopy and the foam together along the outermost contour line. Label the north side of the foam with an N. Set this piece aside.
3. Hold the now smaller photocopy onto a new section of the foam and cut out the next contour line and label the north side. Stack this new piece of foam on top of the first, orienting the north sides the same way.
4. Continue cutting out pieces of foam and stacking them until all contour lines have been cut out.
| 1. Roll out a sheet of clay that is approximately 1 cm thick. Make the sheet as even as possible.
2. Place the photocopy on top of the clay sheet and trace the outermost contour line with a pencil. You should create a shadow of the pencil line on the clay below.
3. Use the pencil, a popsicle stick or fingers to cut the clay along the contour line.
4. Roll out a new clay sheet and trace the next contour line on it. Cut another “pancake” and stack it on top of the first.
5. Continue rolling out, cutting and stacking new clay sheets until all contour lines have been cut out.