Saturday, September 17, 2011

Make a topographic map!

Make a topographic map!

Real topo map
Build your own mountain and make a topo map of it!
A topographic map, or "topo map," is a way to show mountains and valleys on a flat piece of paper. Topo maps are handy and necessary for many uses, including building roads and hiking trails in the mountains. The map shows where the hills and valleys are and how steep they are.
Clay mountain slices and topo map
Topo map maker

What you need:

  • A lump of clay or Play-Doh® about the size of a coffee mug. (Here is a recipe for making your own modeling dough).
  • Piece of cardboard or large tile on which to work the clay
  • Piece of dental floss, about 2 feet (around 60 centimeters) long
  • Ruler
  • Piece of plain, white paper
  • Long pencil
  • 2 toothpicks

What to do:

  1. make a clay mountainPut the lump of clay on the cardboard and shape a mountain about 4 inches high. Making the map is more fun if you make your mountain a little lop-sided or oddly shaped. However, the mountain should be flat on the bottom.
  2. poke holes with pencilUse the long pencil to poke two holes straight down through the center of the mountain. Make sure your two holes go all the way through the mountain.
  3. mark for equal slicesWith the ruler, measure down about 1 inch (2.5 centimeters) from the top of the mountain and make a little dent mark with the pencil. Make two more dent marks lower down on the mountain about 1 inch apart. Or, without using the ruler, just make three marks to divide your mountain into four slices all about the same thickness.
  4. cut slices with dental flossStretch the dental floss until it is taut, wrapping the ends around your fingers so you have a good grip on it. Use the dental floss to cut through the mountain at top-most mark you made. Hold the floss as horizontal (level with the table or floor) as you can.
  5. mark holes and trace around sliceRemove this clay slice and place it on the paper. Use the pencil to carefully trace around it. Push the pencil through one of the holes in the clay and make a dot on the paper; do the same with the other hole. Put the slice aside, but don't squash it. You'll need it again later.

  6. cut another slice, line up, and traceCut a second slice at your next mark down from the top. Lay the second slice over the tracing of the first one, being careful to place the holes in the second sick over the dots on the paper. To line up the holes, poke the two toothpicks through the holes in the slice and line them up with the two dots on the paper. Carefully trace around the second slice. Your tracing will form a circle outside the tracing of the first slice. (If you have "outcroppings" on your mountain, the the second circle could cross into the area of the first circle).
  7. Cut another slice at the next mark down. Line up the holes with the dots and trace it as you did before. Finally, place the bottom slice on the paper, line up the holes, and trace it.
  8. restack slicesStack the slices back up in order on the cardboard. Be sure the holes line up.
  9. Admire your topo map!
Compare the topographic map you have just made to the model mountain. Why are some of the traced lines closer together than others? What kind of slope gives you lines that are close together? What kind gives lines that are far apart? On your topographic map, where are the steepest slopes? Looking at your map, where would be the best place to build a trail to climb to the top of the mountain?

Making a Topo Map

Lesson Suggestions

Making a topo make from clay is a great way for students to
develop an understanding of what the lines on topo maps
represent. A co-worker found this activity online at NASA
Space Place. She tried it and recommended it to me. I added
a variation at the end and decided to write-up the lesson to share with others.

Basic Online Directions: How to Make a Topo Map

• If you use the modeling clay recipe that comes with the directions, you’ll need one batch
of clay for each team or pair. Plan to make it yourself or send home the Modeling Clay
letter a week in advance.
• Read through the directions online so you’ll know what to do. Hint: Test out this lesson
yourself before using it with your students. You’ll be able to give much better directions.
It seems confusing, but the directions makes sense as you work through the steps. You
may want to save your model to use as an example for the class.
• Gather all materials in advance. You can use thin wire instead of dental floss for cutting
slices in the dough.
Supplemental Directions
1. Distribute a lump of dough to each team or pair. Have them place the dough on a paper
plate or tray. Show the online directions to the class and review them together. Then
follow them step-by-step as a class.
2. Ask them to create a lopsided mountain as shown on the directions and make sure they
poke the two holes all the way through all four layers.
3. When it’s time to cut the dough into slices and trace it, make sure students know that
they must carefully transfer the slices to the paper without rotating them. It might help to
draw a North arrow 􀃏 on each slice and a North arrow on the paper to keep everything
oriented properly. As they trace each line, point out that they are creating contour lines
that show each layer’s elevation.
4. After everyone makes their topo maps, collect all the maps and all
the mountains. Assign each mountain a number and each map a letter.
Have students try to match each map to its corresponding mountain.
To do this, they’ll have to look at the shapes of the contours and the
distances between the contour lines. Hopefully they’ll notice that the
closer the lines, the steeper the slope.
5. Assessment Idea - After the lesson is over, create your own
mountain from a lump of extra clay. Make one side extremely steep
and create a gradual slope on the other side. Ask students to draw
what they think the topo map would look like for that mountain.
Have them write about what they learned from the lesson including
what the distances between the lines mean.

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